According to the Soy Foods Association of America, soy flour is derived from soy beans and can add protein and a moist texture to a variety of recipes, from cookies to breads. Soy flour can be used as a substitute for regular, all-purpose flour without dramatically changing the taste. Soy flour should be stored in an airtight container and can be kept for up to one year.
Measure out 3/4 cup of soy flour for every 1 cup of flour called for in the recipe. For instance, a recipe that calls for 2 cups all purpose flour would have 1 1/2 half cups of soy flour added to it.
Stir up the soy flour before placing it into the recipe. This will help prevent the flour from sticking, which can occur when using soy flour.
Complete the recipe as written. No other ingredients must be added with the soy flour in order to finish the dish.