Cut the tomatoes into cubes, place in a large bowl. Peel the onion, cut into quarters, then into slices, add to the tomatoes.
Cut the cheese into cubes and add to the bowl together with the basil leaves, drained and rinsed olives and freshly ground pepper. Season with salt (not too much, as the cheese is salty).
Drizzle with extra virgin olive oil and sprinkle with balsamic vinegar.
