Pick the basil leaves. Save some small leaves to garnish the pasta later. Chop the basil leaves and stem coarsely with a sharp knife.
Peel the onion and garlic and chop into fine slices. Wash the fresh tomatoes and remove the crowns. Then cut them into cubes.
Heat 1 tablespoon of olive oil in a frying pan over medium heat. Fry the onion in the warm olive oil for 7 minutes or until it is soft and light golden brown. Add the garlic and basil stalks and fry them with the onions for a few minutes.
Stir in the tomatoes, a pinch of sea salt and the wine vinegar. Stir the basil leaves into the tomatoes and cook the sauce gently for 10 minutes.
