Measure each flour and starch by lightly spooning into the measuring cup and leveling off with the back of the knife. Thoroughly combine all of the ingredients in a large bowl. Store in an airtight container. For maximum freshness, store in the refrigerator.
Measure flour blend for recipes by lightly spooning into the measuring cup (as opposed to using the cup itself as a scoop) and leveling off with the back of a knife.