Wash the tomatoes and grate / dab them dry. Quarter the cherry tomatoes. Cut the remaining tomatoes in half, clean and chop. Peel and finely dice onion. Peel garlic and chop finely. Wash basil, dab dry and chop the leaves.
Drain mozzarella and cut into cubes. Wash and clean spring onions and cut them diagonally into rings. Put tomatoes, onion, garlic, basil, spring onions and mozzarella in a bowl. Add vinegar and oil and season with salt, pepper and sugar. Cut flat breads in half horizontally and roast on both sides under the grill of the oven. Spread tomato salad on the breads and serve immediately