Measure flours using a digital scale in a clean quart jar.
Measure out warm water into the jar.
Give everything a good stir and put the ring and lid on. Set on counter or in a warm place for 24 hours.
After 24 hours, discard all starter but 40g. Feed the 40g of starter with 65g sorghum flour, 65g brown rice flour, and 125g warm water. Stir everything, put lid and ring back on, and set for another 24 hours at room temperature.
Continue the above process for 5-7 days or until your starter has doubled, has lots of air pockets, and smells sour with a little sweetness. You are now ready to make bread!