Place all of the flours in a large bowl and whisk or stir until completely combined and all flours are evenly distributed. This will take a while to ensure proper blending. Store in a covered container. Refrigerate or freeze the flour if you won’t be using it within 2-3 weeks.
I don’t include xanthan gum in this recipe because some people avoid it, but I generally include ½-¾ teaspoon (2.5-3.5 ml) xanthan gum per cup when I bake with this flour.