Prepare a dough from the flour, baking powder, salt, oil and water and knead well. Divide the dough into 4 pieces and roll out onto a baking tray lined with baking paper. Wash vegetables. Peel the onion and garlic. Finely chop the garlic. Finely dice the courgettes, peppers, onion and olives. Season the strained tomatoes with garlic and spices. Spread the tomatoes on the pizza first, then the vegetables and finally the sour cream. Bake the pizzas at 180 °C in a fan oven for about 30 minutes.