Score the tomatoes crosswise, scald, peel, core and cut the pulp into small pieces. Puree half of the tomatoes. Wash the basil and shake dry, pluck the leaves from the stems and chop them into small pieces. Drain the tuna well in a colander. Mix the diced tomatoes and the tomato puree with the olive oil and vinegar. Peel and squeeze the garlic. Chop the tuna and stir into the tomato sauce with the basil. Season to taste with salt and pepper.
Cook the pasta according to the instructions on the packet, drain, mix with the sauce and serve immediately.