Preheat oven to 400 °F / 200 °C. Cut the pita breads around the edge, so you have 4 half round pita breads. Grate the cheese and divide it on all 4 breads.
Peel the potatoes and slice them very thinly. Divide the slices on all pizzas, make sure to place them out on the edges as well in 1 single layer. Slice the zucchini and place on top of the potato.
Drizzle with some olive oil, salt and pepper and bake in the oven for 15 min, until golden and the potatoes are tender.
Drain the tuna, and arrange half a can of tuna on each of the two baked potato pizzas. Top it with 1 Tbsp capers, some pea sprouts and a drizzle of lemon.
Slice the avocado and place it on the remaining two baked potato pizzas. Top it with pea sprouts and a drizzle of lemon and serve all pizzas straight away.