Traditional Flatbread

From A Feast of Ice and Fire by Chelsea Monroe-Cassel and Sariann Lehrer.
Ingredients:
1 1/2 c. water
4 1/2 tsp. dry yeast (2 packets)
1 tsp. sugar
4 c. flour, plus more as needed
1 tsp. salt
3 Tbsp. olive oil
1 egg, beaten, for glaze
Black sesame or poppy seeds (optional)

To make the sponge, heat 1/2 cup of the water until it is just warm, then dissolve the yeast and sugar in the water and let the mixture stand in a warm place for 10 minutes, until frothy. Stir in 1/2 cup of the flour, cover the bowl loosely with plastic wrap, and let rise for 30 minutes.
Heat the remaining 1 cup water until it is lukewarm. Put the remaining 3 1/2 cups flour in a large bowl, make a well in the center, and add the sponge, salt, olive oil, and lukewarm water. Gradually work this into the flour to make a soft, sticky dough. Knead the dough on a floured surface for 15 minutes, then put the dough in a buttered bowl, cover loosely, and let rise for 1 hour.
Punch the dough down and divide it into quarters, shaping each into a ball. Then loosely cover the balls and let them rest for an additional 30 minutes.
Preheat the oven to 550°F.
Wet your hands and shape each piece of dough into a circle by flattening the dough and stretching it to about a ½-inch thickness. Glaze the round with a generous amount of egg and sprinkle it with seeds, if desired. Press your fingertips firmly into the dough, creating indentations over the whole surface. Bake for 6 to 8 minutes, or until golden. The bread is best served warm with honey, but will keep for several days in an airtight container.
Makes 4 flat loaves.