1. In the bowl of a stand mixer, mix the yeast, sugar and water. Let stand 10 minutes for the yeast to proof.
2. Add the olive oil, flour, salt, and a few good turns of freshly ground black pepper, and knead on medium high-speed with the dough hook attachment until the dough is smooth and elastic, about 5 minutes. You may need to add a sprinkle more of flour if the dough is too wet, or a bit of water if it feels too dry. Cover the bowl with a kitchen towel and let rise 30-45 minutes.
3. Add the scallions to the dough and stir them in with the dough hook. Scrape the dough from the mixer bowl onto a lightly floured countertop and divide the dough into six pieces.
4. Working near the stove, roll each piece of dough into a 5-inch (12cm) round, dusting them with just enough flour (top and bottom) to keep them from sticking to the counter. Once you’ve rolled all six, let them rest five minutes.
5. Heat a cast iron skillet over medium high heat.
6. Roll the first disk into a larger circle, about the size of your skillet. (I used a 10-inch, 25cm, skillet, rolling them into 8-inch, 20cm, circles.) Brush the skillet with a lashing of olive oil and drape the flatbread in the pan. Let cook for 2 minutes on the first side, or until browned and blistered, then turn the flatbread over and cook the other side until it’s blistered as well, about another 2 minutes. While you’re cooking one flatbread, start rolling out the next one and continue with the rest of the circles of dough, brushing the pan with oil between frying each flatbread.