Palestinian Taboon Flatbread (Baked on Pebbles)

Method

1. In a large bowl, whisk together the bread flour, whole wheat flour, salt, and sugar. Make a well in the center and pour in the olive oil, yeast, and warm water. Using your fingers, gradually incorporate the dry ingredients into the wet until a very soft, sticky dough forms. If the dough feels stiff, add water 1–2 tablespoons (15–30ml) at a time until soft and slightly sticky. Let rest 5 minutes, then knead for about 1 minute until smoother (it will still be sticky). Repeat the rest-and-knead process once or twice more until you have a very soft, elastic, and slightly sticky dough.
2. Oil your hands well, gently shape the dough into a smooth ball, rub it all over with olive oil, and place it back in the bowl. Cover with a damp kitchen towel or plastic wrap and let it rise at warm room temperature until doubled in size, about 90 minutes (longer in cooler weather).
3. Once risen, gently punch down the dough to release air. With well-floured hands, divide it into 8 equal pieces, shape each into a ball, and place them on a heavily floured baking sheet or work surface. Cover with plastic wrap and let them rest until they increase in size by about 50%, roughly 30 minutes.
4. Meanwhile, if using optional river rocks, spread them in an even layer in a 10- or 12-inch cast-iron skillet; otherwise, leave the skillet empty. Position the oven rack in the middle, place the skillet on it, and preheat the oven to 500°F or the highest setting. Line a baking sheet with a clean kitchen towel.
5. Working with one dough ball at a time, place it on a floured surface, dust with more flour, and flatten slightly with your hand. Using your hands, flatten and stretch the dough into a rough 4-inch round. Flip it over, adding more flour if sticky, and continue stretching until you have an 8-inch round.
6. If using rocks, carefully pull out the oven rack halfway. Transfer the dough round directly onto the hot skillet, laying it over the pebbles, and gently stretch it into a more circular shape. If not using pebbles, place the dough directly on the hot skillet and use your fingertips to make indentations all over the bread (this mimics the pebbles and prevents the bread from puffing into a pocket).
7. Bake until the top is very lightly golden, about 5 minutes. Using oven mitts or silicone-tipped tongs, carefully lift the taboon from the pebbles. If the bottom is not browned, flip it over and return to the oven for about 1 minute more until lightly golden on the second side. Transfer the baked bread to the towel-lined sheet to cool. Let the rocks and/or skillet reheat for 5 minutes while you stretch the next dough round, then repeat with the remaining pieces. Serve immediately or store in a zip-lock bag at room temperature for up to 1 day, or freeze for up to 1 month.