The hardest part about this recipe is getting hold of emmer flour, which is pretty rare and can be pricey. (If it's unavailable, you can use whole wheat.) But if you do find it, dive in. I tried this recipe with 100 percent emmer flour, but found the taste too assertive, so I mixed it with an equal portion of whole wheat flour. (If you want a milder version, mix the emmer with white flour, but cut back on the water slightly.) Although the recipe calls for the dough to sit for as long as 8 hours, you can use it far sooner, though the flecks of bran may be more noticeable.
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.