Cook the pasta in approx. 4 l boiling salted water (approx. 1 teaspoon salt per litre) according to the instructions on the packet. For the vinaigrette, mix vinegar, salt and pepper. Fold in the oil. Stir in the pesto. Drain the pasta, rinse with cold water and drain.
Mix with the vinaigrette, then leave to cool.
Wash and halve the tomatoes. Cut mozzarella into cubes. Halve slices of mortadella and cut them crosswise into strips. Wash basil, shake dry and pluck the leaves.
Mix pasta, tomatoes, mozzarella, mortadella and basil. Leave to stand for about 30 minutes. Season pasta salad with salt and pepper.