Special equipment: Bowl Plastic wrap Plastic dough scraper l0-inch cast-iron skillet Rolling pin Spatula (optional)
Morning: Combine the flours, water, oil, and salt in a bowl until they come together into a mass. Cover and let sit at room temperature for 20 to 30 minutes while the flour absorbs the water.
Transfer the dough to a lightly floured work surface and knead for about 5 minutes by pushing down on and spreading the dough and then folding it over on itself. It should be smooth and elastic. Form it into a ball and place it in a clean, oiled bowl. Cover with plastic wrap and let the dough rest for 4 to 8 hours.
Afternoon or Evening:
About 45 minutes before you want to bake, spread out the dough on a lightly floured counter, cut the dough in half with a dough scraper, and roll it into 2 logs. Cut each log into 6 pieces. You should have 12 pieces of dough that weigh about 55 grams each; evenly distribute any leftover dough.
Shape each piece into a ball. Let the balls rest for 30 minutes at room temperature under plastic wrap.
Place a cast-iron skillet over medium-high heat and let it heat up for several minutes.
Meanwhile, liberally flour a work surface. Flatten a dough ball and dust it lightly with flour, then use a floured rolling pin to roll it out as thin as possible (7 to 9 inches in diameter), rotating the disk to keep it even. If it resists, let it rest for a few minutes and continue rolling again. Cover the disk with a towel. Repeat with the remaining dough.
When the skillet starts smoking, gently lift a disk of dough. Place it in the skillet, cook it for about 30 seconds, and then turn it over with your fingers or a spatula for another 30 seconds. Remove the skillet from the flame and, holding the flatbread by its edge, put it directly on the fire. Keep moving it in a circle so that it doesn't burn, then turn over and repeat. The bread should be blistered and dark in spots.
Remove the flatbread and cover it with a towel or aluminum foil to keep it from forming a crust. (Dot it with butter and fold it in half if you like.) Repeat with the remaining disks of dough.
Serve warm. These can be made in advance and stored in a resealable plastic container on the counter for a couple of days. But they are best eaten fresh.