1. In a measuring cup mix the sugar, warm water, and yeast. Allow the yeast to bloom (about 10 minutes).
2. Add the yogut to the bowl of a stand mixer with dough hook. Add the flours, salt, and olive oil on top of the yogurt. Pour the bloomed yeast on top of the dry ingredients, then turn the mixer on low until a dough ball forms. Increase to medium-low speed for 1 minute, then turn the mixer off and allow the dough to rest for 5 minutes.
3. Return to medium-low speed for 5 minutes, then rest 5 minutes. Add additional bread flour if the dough seems too wet (the dough should be tacky, not sticky). Repeat two more times.
4. Knead the dough on a floured surface briefly, then place in an oiled bowl and cover to rise in a warm spot for about 2 hours.

The dough should double in size before you bake. To bake:

1. Place a cast iron comal or griddle over medium-high heat for at least 5 minutes.
2. Meanwhile, divide the dough into 8 equal portions. Cover with a towel.
3. When the comal is hot enough (nearly smoking) spray lightly with oil. Stretch a dough portion (as you would a pizza, using a little flour on your hands to prevent sticking) and "slap" onto the comal. When bubbles form in the dough, use tongs to gently flip the loaf. The underside should be gently charred in places. After another minute remove the loaf (the other side should now have the distinctive charred bubble tops) to a basket lined with a towel. Repeat for remaining dough portions.

When the hot loaves are placed inside a towel they will steam slightly, softening the crust that formed where the loaves touched the hot surface.

You can optionally brush the loaves with melted butter and sprinkle with fresh herbs as they finish baking.