Focaccia Bari-style (focaccia Barese)

I ate this focaccia for the first time in Bari from a little bakery called Panificio Santa Rita, in a tiny laneway, off the beaten track. It was mid-morning and I stood outside, as one elderly local after another emerged holding a slice of yeasty dough studded with bright red tomatoes. They stood in a circle outside, chatting between mouthfuls of focaccia. I found out from the fornaio (baker) that the dough is made with potatoes, and that I was lucky to have found any left, as he had usually sold out by this time. You can experiment with other toppings, but tomatoes, olives and oregano are traditional.