Measure 1 cup flour and place in a medium bowl. Remove 2 tablespoons (just place it back in with the rest of your flour).
Add 2 tablespoons cornstarch.
Use a mesh sieve to sift the mixture into a separate bowl. Repeat this process one more time.
If you’re using the mixture for a recipe immediately, measure out the amount needed as you’ve incorporated more air and it will be more than 1 cup at this point.
Store in an airtight container – I use these and love them.
Notes
Measuring Flour: To properly measure flour, use a spoon to fluff up the flour in its container, then use a spoon to scoop it into a dry measuring cup. Use a knife or other straight-edged utensil to level the flour across the top of the measuring cup.