Put the spaghetti in plenty of boiling salted water and let it boil fizzily for about 8 minutes. In the meantime, clean, wash, quarter and seed the tomatoes. Finely dice the flesh. Remove sage leaves from the stems. Cut into narrow strips or leave whole.
Mix with the tomato cubes. Heat the fat in a frying pan, briefly sauté the tomatoes and sage. Add the spaghetti and turn briefly. Slice the parmesan cheese into thin strips with a peeler and pour over the spaghetti. Arrange in portions and serve garnished with fresh sage leaves