In the bowl of a food processor or in a regular large bowl, dissolve the yeast in 1/2 cup warm water, set aside for 5 minutes. Pour salt into this yeast water and add another 1 1/2 cups of warm water, set aside for 10 minutes.
Add flour into the liquid, 1 glass at a time and the rest of the water, knead a homogeneous dough, form a ball, cover the bowl, and put in a warm place to rise for 3 hours.
Turn on the oven to preheat to 250 degrees. Place the matched dough on a floured work surface and knead well. Divide the dough into 6 pieces. Roll each part into an oval about 1 cm thick.
Lightly grease a large baking sheet with foil, put on it the ovals of dough (as much as fit), make dents with your fingers, and sprinkle each oval with 2 teaspoons of sesame seeds. Place the baking sheet in a preheated oven and bake the sangak for 3-4 minutes, then turn the cakes over to the other side and bake for about 2 minutes more. Bake all sangak in this way and serve warm or chilled.