Using All-Purpose Flour Instead of Cornstarch
Ratio
Use 2 tbsp flour per 1 tbsp cornstarch
Good — works well with minor differences
Measurement Variance Note
For 1 cup references, this ingredient can vary by about 6% across brands and measuring methods (120g-136g per cup). For the most reliable substitution result, measure by weight and test a half batch first.
What changes when you swap cornstarch for all-purpose flour
Cornstarch is pure starch; flour is roughly 75% starch padded out with protein and bran. That protein is why you double the quantity (2 tbsp flour per 1 tbsp cornstarch) and why the swap reads differently on the plate — sauces turn matte and opaque instead of glossy, and you'll taste a faint raw-flour note unless the mixture simmers for at least 3 minutes after thickening. Fine for a beef stew or sausage gravy; wrong for a stir-fry glaze or clear fruit pie filling.
- Make a beurre manié or slurry with cold liquid before adding — flour clumps faster than cornstarch and won't disperse if you sprinkle it into hot stock.
- Simmer the thickened sauce for at least 3 minutes after it comes together. Flour needs longer cooking to lose its pasty taste; cornstarch sets almost instantly.
- Skip the swap for glossy Asian sauces, lemon curd, or fruit pie fillings where transparency matters — flour will dull the colour and mute the sheen.