In the absence of wheat, cooked millet provides the structure and chewiness of these flatbreads. The long sourdough fermentation gives them the sweet-savory addictive quality usually missing from "substitute" breads. I make them constantly.
Cultures for Health. The millet and potato flours can be switched out for other things, like teff or tapioca flour. I wouldn't add much more oat flour, or the flatbreads will be hard and dry. Same for rice flour.
Sourdough Millet Oat FlatbreadMakes 18 4-5" flatbreads
In a large bowl, combine:
4 cups cooked millet, cooled somewhat*
2 cups oat flour
1 cup millet flour
1 cup potato flour
Stir to evenly distribute the cooked millet & break up any lumps. Then add:
1/2 cup active sourdough starter
1.5 cups water
Knead briefly to mix everything evenly, then cover with a tea towel and place somewhere warm to ferment.
Let the dough ferment for a few hours, depending on the temperature. My kitchen has been in the 90s lately, so a few hours are plenty, but each rising can take 8 hours or more when it's down in the low 60s in the winter. The dough will not really rise, either--that's a lot to ask of a bread without gluten. Instead, it will puff slightly, develop cracks in the surface, and become fragrant with sourdough as the starter reproduces. The dough will also soften considerably as it absorbs moisture from the cooked millet, and you'll need to stir it rather than knead it. Let it rise again for a similar amount of time.
When it has puffed and cracked a second time, whisk together:
3 tablespoons of honey
1/4 cup olive oil
1.5 teaspoons of sea salt
Pour over the dough and stir until well combined. With the honey and olive oil, the dough will be quite wet now.
Line two large baking trays with parchment and pour 1/4 cup olive oil in a little bowl. Scoop large spoonfuls of batter onto the trays, about 9 per full-size sheet tray. Oil your hand well and pat the spoonfuls down into smooth 5" circles. Dip a little more oil onto your hand before patting each flatbread. They should be quite oily on top, so pat on a little extra if you have any oil leftover at the end. Let the flatbreads "rise" again until a bit puffier, another hour or two.
Bake at 400 degrees for 10 minutes, then switch the baking sheets and bake for another 10 minutes. They should be golden all over and a bit brown at the edges. Use convection if you have it, or run each tray under the broiler for a minute at the end to get some extra color on them. Let cool on a rack.
After the first day or two they'll definitely need to be toasted to be delicious. They freeze well and can be toasted from the freezer.
Seeded flatbread: Add 1/2 cup each chopped walnuts, sunflower seeds, pumpkin seeds, and 2 tablespoons sesame seeds to the dough with the honey and olive oil after the first two risings.
Note: Over the course of a long fermentation, the enzymes in honey can have unpredictable effects on bread dough. Saving the oil for the end makes the honey easier to mix in. The honey is delicious, of course, encourages browning, gives the yeast a little boost for that final rise, and helps the flatbread retain moisture, but you could certainly omit it and add the oil and salt when first mixing up the dough.
*Rinse & drain 1 part millet and add 2 parts water, bring to a boil, then turn down and simmer for 20 minutes until the liquid is absorbed.