Rinse and drain the peas. Blanch the tomatoes then once dried, deseed and peel them; drain them in a colander for 15 minutes, dice the cubes. Chop the onion finely, place it in a pan with butter and oil and fry until soft.Add the peas, a pinch of salt and pepper and a few tablespoons of water. Simmer for 20 minutes, towards the end add a few chopped leaves of basil. Add the tomatoes and cook over a high heat for 5-6 minutes. Cook the pasta in boiling salted water, drain al dente then mix it with the vegetable sauce.