Combine in a resealable container. Shake well to evenly distribute.
If the recipe calls for 1 cup:
Measure 2 Tablespoons corn starch into a 1 cup measuring cup. Fill the remainder of the cup with AP Flour.
If the recipe calls for 1/2 cup:
Measure 1 Tablespoon corn starch into a 1/2 cup measuring cup. Fill the remainder of the cup with AP Flour.