Melt the yeast in a bowl with water at room temperature. (If you want to prepare the Bari focaccia with sourdough, you will have to refresh it twice and then break it up in the water before proceeding as per the recipe, for leavening instead, the times will be around 12 hours). Boil the potatoes and mash it. 

Add the two flours, the mashed potatoes work the dough in a manner vigorous for about 5 minutes then add 1 tablespoon of oil and salt. Knead for a long time until you get a homogeneous dough, shape a ball, place in a bowl greased with oil, cover and let rise for 2 hours Slide the focaccia dough onto an oiled pan Roll out the dough with your hands.

Once the dough is rolled out, break the cherry tomatoes in half with the hands to let all the juice run out and place them facing downwards, until the entire surface of the focaccia is filled. Now put the olives, oiled again, add a pinch of salt and of dried oregano. Bake in a preheated oven at 200° and cook for 20 minutes.