1. Heat the oil in a saucepan and add the onion, garlic, green pepper and crushed hot red pepper. Cook, stirring often, for about 5 minutes.
2. Add the tomatoes, bay leaf, thyme and a generous grinding of pepper. Bring to a boil and simmer 20 minutes.
3. Spoon mixture into the container of a food processor. Blend to a fine puree. Add the basil. Reheat. Swirl in the margarine. Serve over spaghetti This sauce freezes well.