In a large bowl, place the 6 cups white rice flour , 3 ¼ cups oat flour, 1 ¾ cups tapioca flour, 1 ¼ cups potato starch, and ¼ cup ground psyllium husk. Whisk to combin very well. Store in an airtight container in the pantry. Before using, give the container a good shake to redistribute the flours.
Notes
Do I need to use these exact flours? You can experiment with the varieties of flour used here, but make sure to keep the ratio of gluten-free flours to starch the same so that the mix is balanced. Keep in mind that using a flour like buckwheat will have a stronger flavor than white rice flour.
Make a bigger batch. This recipe makes a lot of bread flour mix, which is so handy! I love not having to weigh and measure flours every time I want to bake. You can definitely double the quantities if you want to keep even more on hand.
Measure the flours by weight. When preparing the mix, you'll have the best overall results if you measure the gluten-free flour out by weight. This ensures complete accuracy. Otherwise, use the spoon and level method to measure the flour.
Mix well. Make sure to stir and whisk the gluten-free flours together very well so that they are well mixed. When you transfer to your storage container, give the container a shake, and give the mix a shake and a whisk each time you go to use it to redistribute the flours.