Cornstarch substitutes

Cornstarch substitutes — 7 options, ranked, with the exact amount

Also called cornflour, corn starch, maize starch, cornstarch powder

Use thisBest of 7 options

Use All-purpose flour

2 tbsp for every 1 tbsp cornstarch

For a gravy or a pan sauce, use 2 tbsp all-purpose flour per 1 tbsp cornstarch, whisked into cold liquid first and then simmered a full two minutes longer than you would cornstarch so it loses its raw taste — it will be cloudy rather than glossy. If you need the sauce to stay clear, use arrowroot 1:1 instead and take it off the heat as soon as it thickens.

Verdict —: Tweak it
The tweak —: Whisk it into ¼ cup of cold liquid until there are no lumps, stir that into the hot pan, and simmer at least 2 minutes longer than you would for cornstarch
Best for —: gravies, stews, chowders and anything already opaque
Pantry —: Likely in your cupboard

Checked 22 Jul 2026 · no sponsored swaps

But first: what’s the cornstarch doing?

Pick your case

What are you thickening, and does it need to look clear?

Cloudiness does not matter here, so flour is the right answer and you almost certainly have it. Use 2 tbsp flour per 1 tbsp cornstarch, whisk it into cold liquid or cook it in butter first, and simmer it a full two minutes longer than you would cornstarch.
Notes on all-purpose flour
2 tbsp per 1 tbsp
Flour will turn it grey and opaque. Use arrowroot or tapioca starch at 1:1, stir it in at the very end, and pull the pan off the heat the moment it thickens. Both give a clearer, glossier finish than cornstarch, and both thin out again if you keep boiling them.
Notes on arrowroot powder or tapioca starch
1 tbsp per 1 tbsp
Use flour at 2 tbsp per 1 tbsp of cornstarch, not arrowroot or tapioca. Arrowroot's gel is slack, goes slimy with dairy and breaks down on reheating, so a cream pie made with it will not slice.
Notes on all-purpose flour
2 tbsp per 1 tbsp
Starch is the wrong family. Use xanthan gum at ¼ tsp per cup of liquid, sprinkled slowly while whisking, which thickens cold and does not break down when reheated. It is a different mouthfeel and it is the only thing here that works this way.
Notes on xanthan gum
¼ tsp per cup liquid
There it is diluting the flour's protein to make things more tender, not thickening anything. Replace it with the same volume of all-purpose flour and accept a slightly chewier, less crumbly result. Do not use arrowroot or potato starch here.
Notes on all-purpose flour
2 tbsp per 1 tbsp

Two questions decide it. Does it need to look clear? If yes, use arrowroot or tapioca starch 1:1 and take the pan off the heat the moment it thickens. If no — gravy, stew, cheese sauce — use 2 tbsp flour per 1 tbsp cornstarch and simmer two minutes longer than you think you need to. Then ask whether the dish has to set, be reheated, or be frozen. Setting and reheating both mean flour; freezing means tapioca; neither means arrowroot or potato starch, which break down with heat and time.

Job by job3 jobs

Cornstarch is pure starch doing one thing: its granules swell above about 150F and crowd together, which is what turns watery pan juices into gravy. Added dry, or never simmered, it does neither.

Bindingsecondary

Dry, it soaks up surface moisture and forms a thin brittle shell in hot oil, which is why cornstarch-dredged chicken goes crisp and stays crisp longer than flour-dredged chicken does.

Thickeningprimary

Heated in liquid past roughly 150F its granules swell many times their size and get in each other's way, which is what turns watery pan juices into gravy that coats the back of a spoon.

Setting & gellingsecondary

As a cooked starch gel cools it firms up further, enough that a slice of banana cream pie holds its shape on the plate — though it is a soft set that slumps if you cut it warm, not a gelatine set with a clean edge.

Every option, one card

Ranked · per 1 tbsp cornstarch

Cornstarch substitutes compared
#	Substitute	Instead of 1 tbsp cornstarch	Verdict
1	All-purpose flourgravies, stews, chowders and anything already opaque	2 tbspTweak it	Tweak it
2	Arrowroot powderclear glazes, fruit sauces and stir-fry sauces where shine matters	1 tbspTweak it	Tweak it
3	Tapioca starchfruit pies and cobblers, where it stays clear and does not weep after freezing	1 tbsp, stirred into 2 tbsp cold waterTweak it	Tweak it
4	Potato starchthickening a soup or sauce right at the end of cooking	1 tbsp, stirred into 2 tbsp cold waterTweak it	Tweak it
5	Instant mashed potato flakessoups, stews, chowders and chilli	2 tbsp, sprinkled straight into the simmering potYou'll taste it	You'll taste it
6	Rice flourgluten-free gravies and stews	2 tbsp white rice flourYou'll taste it	You'll taste it
7	Xanthan gumcold sauces, dressings and smoothies that cannot be cooked	¼ tspYou'll taste it	You'll taste it

What changesWhat changes, option by option7 options

All-purpose flour

fuller and slightly wheaty; if under-simmered, unmistakably raw and pasty

Wheat flour, which is only about three-quarters starch — the rest is protein and bran, which is why you need twice as much and why the sauce turns cloudy.

Covers: Binding; Thickening; Setting & gelling

What these mean

Amount: 2 tbsp all-purpose flour for 1 tbsp cornstarch
Then: whisk it into ¼ cup of cold liquid until there are no lumps, stir that into the hot pan, and simmer at least 2 minutes longer than you would for cornstarch
Best for: gravies, stews, chowders and anything already opaque, puddings and cream pies that must slice, when the sauce will be reheated or frozen
Texture: softer and more velvety than cornstarch's slightly slick body, and it holds up to reheating and freezing where cornstarch weeps
Look: matte and opaque instead of glossy and translucent. A fruit glaze goes from jewel-clear to greyish, and a stir-fry sauce loses its shine entirely
Pantry: Likely in your cupboard
Suits: vegan, vegetarian, dairy-free
Contains: wheat

Use twice as much: 2 tbsp flour per 1 tbsp cornstarch. Flour is roughly 75% starch, so a spoonful carries less thickening power.
Simmer for a full 2 minutes after it thickens, minimum. Under-cooked flour tastes distinctly of raw dough and no amount of seasoning covers it.
Better still, cook it in fat first: melt 2 tbsp butter, stir in the 2 tbsp flour, cook 1-2 minutes until it smells nutty, then whisk in the hot liquid off the heat. That is a roux and it eliminates both lumps and the raw taste.
If you whisk it into cold liquid instead, use cold — not warm — and pour the slurry into the pan while stirring, never the other way round.

The most reliable swap and the one already in the cupboard. The two things people get wrong are using it 1:1, which gives a thin sauce, and not simmering it long enough, which gives a sauce that tastes of flour paste.

Not for anything that must look clear, and not for gluten-free cooking.

Arrowroot powder

completely neutral, cleaner than cornstarch

A pure starch ground from the root of the arrowroot plant, which thickens at a lower temperature than cornstarch and gives a clearer, glossier result.

Covers: Thickening
Misses: Binding — not covered; Setting & gelling — not covered

What these mean

Amount: 1 tbsp arrowroot powder for 1 tbsp cornstarch
Then: stir into 2 tbsp cold water, add at the very end of cooking, and take the pan off the heat as soon as it thickens
Best for: clear glazes, fruit sauces and stir-fry sauces where shine matters, acidic sauces with lemon, wine or vinegar, which weaken cornstarch, gluten-free and grain-free cooking
Taste: completely neutral, cleaner than cornstarch, with none of cornstarch's faint chalkiness
Texture: lighter and less slick, with a slightly stretchy quality; a slack gel rather than a firm one
Look: the clearest and glossiest option on this page — a fruit glaze looks like glass
Suits: vegan, vegetarian, gluten-free, dairy-free

Add it in the last minute of cooking. It thickens from around 150F, well below a simmer, so it is ready sooner than cornstarch.
Take the pan off the heat immediately once it thickens. Held at a boil, arrowroot breaks down and the sauce thins out again — this is its one real weakness and it is not a measuring error.
Do not use it with milk or cream. Arrowroot and dairy together go unpleasantly slimy and stringy.
Do not reheat an arrowroot-thickened sauce more than once; it loses body each time.

Better than cornstarch for a clear acidic glaze and worse for almost everything involving milk or a long cook. The 1:1 is easy; the timing is the part that decides whether it works.

No dairy, no long simmering, and no cream pies or puddings that need to set firm enough to slice.

Tapioca starch

neutral, very slightly sweet

Starch extracted from cassava root, also sold as tapioca flour, which thickens fast at a low temperature and sets to a glossy, faintly stretchy gel.

Covers: Thickening
Misses: Binding — not covered; Setting & gelling — not covered

What these mean

Amount: 1 tbsp tapioca starch, stirred into 2 tbsp cold water for 1 tbsp cornstarch
Then: add in two halves, stirring 30 seconds between them, and stop when the sauce coats the back of a spoon and a finger drawn through leaves a clear line
Best for: fruit pies and cobblers, where it stays clear and does not weep after freezing, sauces you want visibly glossy, gluten-free and grain-free baking
Texture: distinctly stretchy and a little chewy — good in a fruit pie, odd in a savoury gravy
Look: high-gloss and clear, the shine you see on a bakery fruit tart
Suits: vegan, vegetarian, gluten-free, dairy-free

Add it in two stages with 30 seconds between. It thickens very fast at low heat, and it is easy to overshoot into something gluey.
Stop when the sauce coats the back of a spoon and a finger drawn across leaves a clear line that does not close up.
Do not boil hard once it has thickened, and do not hold it hot for long. Like arrowroot, it thins out with prolonged heat.
Tapioca starch and tapioca flour are the same thing on most labels. Pearl tapioca and instant tapioca are not — those are granules that need soaking and are measured differently.

The one thickener that survives freezing and thawing without weeping, which is why it is the standard choice for fruit pies destined for the freezer. That stretchy quality is a feature there and a liability in gravy.

Fruit fillings and glazes. Its stringiness is noticeable in savoury sauces, and it does not give a sliceable cream pie.

Potato starch

neutral, with a faint earthiness in a delicate sauce

Starch washed out of potatoes, which thickens at the lowest temperature of any starch here and breaks down the fastest if it boils.

Covers: Thickening
Misses: Binding — not covered; Setting & gelling — not covered

What these mean

Amount: 1 tbsp potato starch, stirred into 2 tbsp cold water for 1 tbsp cornstarch
Then: stir it in at the very end, off the boil, and serve within a few minutes
Best for: thickening a soup or sauce right at the end of cooking, Passover and gluten-free cooking, when you want thickening without cloudiness and are serving immediately
Texture: silky and slightly slippery, thinner-bodied than cornstarch
Look: clear and glossy while hot; if it has been boiled or held, visibly watery around the edges of the plate
Suits: vegan, vegetarian, gluten-free, dairy-free

Take the pan off the boil before it goes in. Potato starch loses its thickening power quickly above a simmer, faster than arrowroot does.
Serve within a few minutes. A potato-starch sauce kept warm on the stove will thin out.
Do not confuse potato starch with potato flour. Potato flour is cooked, ground whole potato — it tastes of potato and behaves completely differently.
Do not use it in baking recipes calling for cornstarch; it absorbs far more water and makes doughs gummy.

The most heat-sensitive starch on the list, which makes it excellent for a finishing swirl into soup and unsuitable for anything that sits. Add it last, off the heat, every time.

Last-minute thickening of something served straight away. Not for anything reheated, held, frozen, or baked.

Instant mashed potato flakes

adds a mild potato flavour

Cooked, dried, flaked potato that rehydrates on contact with hot liquid and thickens by absorbing it rather than by gelatinizing.

Covers: Thickening
Misses: Binding — not covered; Setting & gelling — not covered

What these mean

Amount: 2 tbsp instant potato flakes, sprinkled straight into the simmering pot for 1 tbsp cornstarch thickening about 1 cup of liquid
Then: stir and wait 2 minutes before adding more, since they keep absorbing
Best for: soups, stews, chowders and chilli, when there is no starch or flour in the house at all, when you want body rather than gloss
Taste: adds a mild potato flavour, which disappears entirely in a beef stew and is obvious in a delicate broth
Texture: hearty and slightly grainy rather than smooth and glossy — body, not shine
Look: cloudy and matte, with a faintly speckled look if you added them too fast
Pantry: Likely in your cupboard
Suits: vegetarian, gluten-free

No slurry needed. Sprinkle them straight into the simmering pot while stirring — this is the one thickener on the page that does not clump.
Wait 2 minutes before judging. They keep swelling, and a pot that looked thin will be right by the time you serve it.
Reduce the recipe's salt slightly if you are using a seasoned or buttered flake mix; read the packet.
Do not use them in a clear sauce, a fruit filling, a pudding or anything sweet.

Included because it is genuinely in more cupboards than arrowroot and it is the fastest fix for a thin stew. It reheats and freezes without weeping, which starch slurries often do not.

Savoury soups and stews only. This is a rescue for a watery pot, not a thickener for a sauce you want to look good.

Rice flour

neutral once properly cooked, faintly cereal-like

Finely milled white rice, which thickens like flour but without gluten, and which needs longer cooking to lose its grain.

Covers: Binding; Thickening
Misses: Setting & gelling — not covered

What these mean

Amount: 2 tbsp white rice flour for 1 tbsp cornstarch
Then: whisk into cold liquid, then simmer 3-4 minutes so the grains soften and stop feeling gritty
Best for: gluten-free gravies and stews, coating fried food, where its lack of gluten keeps the crust crisp, sauces that will be reheated
Texture: slightly grainy compared with any of the pure starches, and it can feel sandy if rushed
Look: opaque and matte, much like wheat flour
Suits: vegan, vegetarian, gluten-free, dairy-free

Use twice as much, as with wheat flour: 2 tbsp per 1 tbsp cornstarch.
Simmer 3-4 minutes, longer than you would for wheat flour. Under-cooked rice flour feels sandy on the tongue.
Choose white rice flour, not brown, unless you want its nuttiness in the sauce.
Look for superfine or Asian-market rice flour if you can; coarser supermarket grinds are the ones that stay gritty.

Useful mainly as the gluten-free equivalent of the flour route, and best where the sauce is rustic enough that a little graininess does not register.

Not for clear sauces, puddings or fillings that must set. Its texture is the reason it sits low on this list.

Xanthan gum

no flavour at all

A polysaccharide made by fermenting sugar with a bacterium, which thickens liquid cold, needs no cooking, and holds its thickness through boiling, chilling and reheating.

Covers: Thickening
Misses: Binding — not covered; Setting & gelling — not covered

What these mean

Amount: ¼ tsp xanthan gum for 1 tbsp cornstarch thickening about 1 cup of liquid
Then: sprinkle it over the surface in a thin stream while whisking hard, or blend it in — never tip it in as a spoonful
Best for: cold sauces, dressings and smoothies that cannot be cooked, sauces that will be reheated several times, gluten-free and very low-carbohydrate cooking
Texture: distinctly different — slippery and slightly gummy rather than the clean body of starch, and it clings to the spoon in a way cornstarch does not
Look: translucent and glossy, sometimes with a faint stringiness where it was added too quickly
Pantry: Special trip
Suits: vegan, vegetarian, gluten-free, dairy-free

Use ¼ tsp per cup of liquid and no more at first. It is roughly ten times as powerful as cornstarch by weight, and this is the substitution people most often overshoot.
Sprinkle it in a fine stream while whisking, or add it through a blender. Tipped in as a lump it forms slimy strings that never disperse.
Wait a full minute before judging the thickness. It keeps developing after you stop whisking.
No heating is required, and heating does not help. This is not a starch.

The only option here that works cold and survives repeated reheating, which is exactly why it is in commercial sauces. It is also the easiest to ruin: a heaped quarter teaspoon instead of a level one makes a sauce feel like slime.

Never in a pudding, cream pie or fruit filling that has to set and slice. It thickens without ever setting.

Don’t swap it here

5 cases

SafetyHome canning — thickening a pie filling, soup or sauce before it goes into jars.Can the fruit unthickened and thicken it when you open the jar, or use a tested recipe with Clear Jel. See the National Center for Home Food Preservation.
Arrowroot, tapioca or potato starch in a milk or cream sauce, a pudding, a pastry cream or a cream pie.Use cornstarch, or 2 tbsp flour per 1 tbsp cornstarch. For a firm sliceable set, flour is more reliable than any of the root starches.
Any starch stirred in dry, straight into a hot pan.Always mix it into cold liquid first — 2 tbsp cold water per tablespoon of starch — or cook it in fat as a roux. The only exception on this page is instant potato flakes.
Adding more xanthan gum because the sauce still looks thin.Add ¼ tsp per cup, whisk, wait a full minute, and only then decide. If it is already slimy, dilute with more liquid — that is the only remedy.
Reheating or freezing a sauce thickened with arrowroot or potato starch.Use flour for anything you will reheat, and tapioca starch for anything you will freeze.

Safety

2 notes

Canning
Do not add cornstarch, flour, arrowroot or tapioca to a home canning recipe. Thickeners slow heat penetration into the jar, so the centre may not reach a safe temperature during processing, and only Clear Jel — a modified starch tested for this purpose — is approved for canned pie fillings. Never alter the ingredients or acidity of a tested canning recipe.
Source — National Center for Home Food Preservation (opens in a new tab)
Allergen
Cornstarch, arrowroot, tapioca, potato starch, rice flour and xanthan gum are all gluten-free. Wheat flour is not. Xanthan gum is usually fermented on a corn substrate, which matters only for a strict corn allergy.
Source — FDA gluten-free labeling (opens in a new tab)

If it went wrong

5 fixes

There are white lumps through the sauce.The starch went in dry, or the slurry was made with warm liquid, so the outsides gelatinized and sealed dry powder inside.Pour the sauce through a fine sieve, pressing the lumps against the mesh. Then make any further slurry with cold liquid and pour it into the pan while stirring.
The sauce thickened nicely and then went thin again.Arrowroot or potato starch held at a boil, or an acidic sauce that broke the starch down. Both lose thickening power with prolonged heat.Whisk 1 tsp of flour into 1 tbsp of cold water, stir it in, and simmer two minutes. For the future, add arrowroot and potato starch off the heat, and use flour for anything that has to sit.
It tastes pasty and raw.Flour or rice flour that was not cooked long enough. Cornstarch needs only a brief simmer; wheat flour needs a couple of minutes and rice flour three or four.Keep simmering, stirring, for another 3 minutes. It genuinely does go away. A knob of butter whisked in at the end helps cover what is left.
The sauce is slippery and slimy and clings to the spoon in strings.Too much xanthan gum, or xanthan tipped in rather than sprinkled while whisking.There is no removing it — dilute with more stock, water or cream until it feels normal, then reseason. Next time use a level ¼ tsp per cup and wait a full minute before adding more.
The cream pie or pudding never set and is soupy in the fridge.Either arrowroot, tapioca or potato starch was used, none of which set firm, or the mixture was never brought to a proper boil, which cornstarch needs to finish thickening.Scrape it back into a pan, whisk in 2 tbsp of flour slaked in ¼ cup cold milk, bring to a full boil for 1 minute while whisking, then rechill for at least 4 hours.

Measure it

8 measures

1 tbsp cornstarchabout 8 gEnough to thicken 1 cup of liquid to a medium gravy that coats a spoon.
Flour equivalent2 tbsp flour per 1 tbsp cornstarchWheat flour is only about 75% starch; the rest is protein and bran, which is both why you need double and why the sauce turns cloudy.
Xanthan gum equivalent¼ tsp per cup of liquidRoughly ten times as strong as cornstarch by weight. Measure it level.
Slurry ratio1 tbsp starch to 2 tbsp cold liquidCold, not warm. Warm liquid starts gelatinizing the outside of the grains and you get lumps in the slurry itself.
Thickening temperaturecornstarch about 150-160F and needs a brief simmer to finish; arrowroot and potato starch thicken lower and break down above a simmerThis single difference explains most of the timing advice on this page.
Cake flour from cornstarch1 cup all-purpose flour minus 2 tbsp, plus 2 tbsp cornstarchSift twice. This is the other job cornstarch does in baking — diluting the flour's protein for a more tender crumb.
Cornflour namingin the UK, Australia and New Zealand, cornflour means cornstarchIn the US, corn flour is finely ground whole corn and will not thicken a sauce the same way. Check which country the recipe is from.
Approved canning thickenerClear Jel is the only starch tested for home-canned pie fillingsRegular cornstarch, flour and tapioca are not approved for canning.

Questions

10 questions

Can I use flour instead of cornstarch?

Yes — use 2 tbsp flour per 1 tbsp cornstarch, because wheat flour is only about 75% starch. Whisk it into cold liquid or cook it in butter as a roux first, then simmer at least 2 minutes longer than you would for cornstarch so it loses its raw taste. The sauce will be opaque and matte rather than glossy and translucent, which is fine for gravy and wrong for a fruit glaze.

What's the best cornstarch substitute for a clear, glossy sauce?

Arrowroot powder at 1:1, or tapioca starch at 1:1. Both give a clearer, shinier result than cornstarch itself. The catch is heat: both thicken below a simmer and both break down if you keep boiling them, so stir them in at the very end and take the pan off the heat as soon as the sauce coats a spoon.

Is cornflour the same as cornstarch?

It depends where the recipe is from. In the UK, Ireland, Australia and New Zealand, cornflour means exactly what Americans call cornstarch. In the US, corn flour is finely ground whole corn — closer to fine cornmeal — and it will not thicken a sauce the same way. If a British recipe says cornflour, reach for the cornstarch box.

Why do I need to mix cornstarch with cold liquid first?

Because starch granules gelatinize on contact with hot liquid. Dropped in dry, the outside of each clump swells and seals instantly, trapping dry powder inside, and you get white pellets that never break down. Cold liquid separates the granules before any of them can swell. Use 2 tbsp cold water per tablespoon of starch, and pour the slurry into the pan rather than the pan into the slurry.

Can I use xanthan gum instead of cornstarch?

For thickening, yes, at about ¼ tsp per cup of liquid — roughly a tenth the amount, because it is far stronger. It also works cold and survives reheating, which no starch does. Sprinkle it in while whisking or add it through a blender, wait a full minute before judging, and never use it for a pudding or pie filling that has to set and slice: it thickens without ever setting.

Which cornstarch substitute works for a cream pie or pudding that has to slice?

Flour, at 2 tbsp per 1 tbsp cornstarch, and bring it to a full boil for a minute. Arrowroot, tapioca and potato starch all make a slack gel that will not hold a cut edge, and arrowroot turns slimy in dairy on top of that. This is the one job where the root starches are simply the wrong tool.

Can I thicken a canned pie filling with cornstarch?

No. Cornstarch, flour and tapioca all slow heat penetration in a sealed jar, so the middle may not reach a safe temperature during processing. Only Clear Jel, a modified starch tested for canning, is approved for home-canned pie fillings. The safe alternative is to can the fruit unthickened and thicken it when you open the jar. See the National Center for Home Food Preservation.

Why did my cornstarch sauce go thin again?

Usually one of three things: it was boiled hard or held hot for a long time, an acidic ingredient such as lemon juice or vinegar went in before it thickened, or it was over-stirred after thickening, which physically tears the swollen granules. Add acid after thickening, take it off the heat once it coats a spoon, and stir gently from then on.

How much cornstarch does it take to thicken a cup of liquid?

About 1 tbsp (8 g) for a medium sauce that coats the back of a spoon, roughly gravy thickness. Half that gives a light glaze; two tablespoons gives something closer to a pie filling. Remember that a starch sauce thickens further as it cools, so stop while it still looks slightly thinner than you want it.

What can I use if I have no starch and no flour at all?

Instant mashed potato flakes, at about 2 tbsp per cup of liquid, sprinkled straight into a simmering pot — no slurry needed. They add a mild potato flavour that vanishes in a stew and is obvious in a delicate broth. Failing that, simply simmer the pot uncovered and let water evaporate; reduction thickens without adding anything at all.

Tips for substituting cornstarch

9 tips

Every starch here except instant potato flakes must be mixed into cold liquid before it meets the hot pan: 1 tbsp starch to 2 tbsp cold water. Dry powder into hot liquid gives permanent lumps.
Cornstarch needs to reach a simmer to finish thickening. Pulled off at 140F it stays thin and tastes chalky, which is the single commonest reason a cornstarch sauce disappoints.
Arrowroot and potato starch go in the other direction: they thicken below a simmer and break down above one. Add them at the end, off the heat.
Acid weakens cornstarch. In a lemon or vinegar-heavy sauce, either use arrowroot or add the acid after the sauce has thickened.
A roux beats a slurry for flour: cook 2 tbsp flour in 2 tbsp butter for a minute or two until it smells nutty, then whisk in the hot liquid off the heat. No lumps and no raw taste.
For a fruit pie you plan to freeze, use tapioca starch. Cornstarch and flour both weep watery liquid after freezing and thawing.
Cornstarch also does a second job in baking, where it dilutes flour's protein for a tenderer crumb: 1 cup all-purpose flour with 2 tbsp removed and 2 tbsp cornstarch added, sifted twice, makes a workable cake flour.
In the UK and Australia, cornflour means cornstarch. In the US, corn flour is ground whole corn and behaves completely differently — check where the recipe comes from before you buy.
A starch-thickened sauce keeps thickening as it cools, so stop while it looks slightly thinner than you want it on the plate.

Sources — National Center for Home Food Preservation (opens in a new tab), FDA gluten-free labeling (opens in a new tab)

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