For the cold spaghetti with tuna, cook the spaghetti for about 9 minutes until al dente. Drain in a colander and let cool – quench if necessary.
Put tuna with juice in a bowl and finely dice the tomatoes. Mix both and season with vinegar and oil – finally season with salt and pepper. Arrange the cold spaghetti with tuna on a plate with basil pesto and olives.