for the sponge:
Mix the sponge ingredients together in a bowl, and set it aside for 4 hours (or up to 16 hours), until the mixture is bubbly and has a nice aroma.

for the dough:
Transfer the sponge to the bowl of a mixer. Add the dough ingredients and mix until it becomes smooth (the dough will be soft but not sticky); adjust its consistency with additional flour or water, if necessary. Divide the dough into 8 balls, about the size of a tennis ball. Let them rest, covered, for half an hour in the refrigerator while the grill or oven is heating.

To grill: Stretch each ball into an oval shape about ¼ inch thick. Brush with oil, then lay the oiled side of the dough down on a clean, hot grill. After 1 minute, turn it 45°, and put it back down to cook for another minute; it will puff up a bit. Oil the top, then turn it over, cover the grill, and cook for 2 minutes to finish.

To bake: Place dough on a parchment-lined baking sheet (or directly on a baking stone), and bake it on the bottom rack of a heated 450° oven for 6 to 8 minutes, until it’s puffed and golden.

Related Recipe: Asparagus Flat Bread