In a medium bowl, whisk together the brown rice flour, teff flour, and water until you have a paste that has the consistency of hummus.
If your paste is thicker, add a very small amount of water and whisk.
Make sure to incorporate air into it.
Cover the bowl with a kitchen towel and let it ferment for about 12 hours or until the sponge has a mousse-like texture when you run a spoon through it.
Measure 75 grams of the starter into a medium bowl.
Discard the rest.
Whisk in the same amount of brown rice flour, teff flour, and water as in the first feeding.
Cover the bowl with a kitchen towel and ferment for about 12 hours or until it has a mousse-like texture.
Repeat the process every 12 hours for a total of 10 feedings (5 days).
By day 3, you should see bubbles and aeration after 12 hours.
Right after the tenth feeding, transfer the starter to a mason jar (anything from a 12-ounce to a 1-quart/1 L jar will work well) and let it ferment for 12 hours or until it is bubbly.
The starter is ready to be used.
