1In a small bowl, dissolve 5g of dry yeast and 1 tsp sugar in 220ml of warm water.
2In a large bowl, mix 00 flour and semolina flour. Pour in the yeast mixture and mix. Add 1 tsp salt and the mashed potato, then gradually add the remaining water.
3Add the olive oil and knead the dough for 5–10 min.
4Divide the dough into 2 equal pieces, shape into balls, place in oiled bowls or pans, cover, and let rise at room temperature for 2.5 hrs.
5Meanwhile, soak the whole Campari tomatoes in a bowl of cold water with a few tablespoons of salt for 1 hr.
6Oil your baking pans well. Gently press and stretch each dough ball to fill its pan.
7Press the soaked tomatoes into the dough, squashing them with your fingers. Top with black olives, oregano, a heavy drizzle of EVOO, and a pinch of sea salt.
8Let the focaccia rest uncovered for 30 minutes at room temperature.
9Bake at 500°F for 10 min on the bottom rack, then 10-15 minutes on the top rack, until golden and crisp on the edges.