Cook the tortellini in salted water according to the instructions on the packet, drain and rinse in cold water. Allow to cool slightly.
For the pesto, cut the sun-dried tomatoes into strips. Finely grate the cheese. Peel off the garlic cloves and chop finely. Now grind the dried tomatoes, grated cheese, cashew nuts, basil and garlic in a blender to a firm paste, then mix in the oil. Now dilute the paste with the balsamic vinegar and, if necessary, some water to a creamy consistency and season with salt and pepper if necessary. Mix with the tortellini in a bowl.
Now halve or quarter the cocktail tomatoes depending on their size. Dice the mozzarella and halve the olives if desired. Mix everything with the tortellini and let it steep for a while covered.