Place the tortellini in boiling salted water. Leave to stand over a low heat for 2-4 minutes. Drain. Roast pine nuts in a pan without fat. Take out and let cool down. Wash and halve the tomatoes.
Drain mozzarella well.
For the marinade, mix vinegar, pesto, salt, pepper and 1 pinch of sugar. Fold in the oil. Season to taste again. Wash the basil and remove the leaves from the stems.
Carefully mix tortellini, tomatoes, basil, mozzarella, pine nuts and marinade. Leave to stand for at least 30 minutes. Season again and arrange on a plate.