Heat oil in deep saucepan over medium heat. Add onion, pepper and garlic; cook 5 minutes, stirring occasionally. Do not brown garlic.
Add clam sauce and tomato paste. Partially cover pan. Simmer, stirring occasionally, for 20 minutes.
Spoon half of sauce over hot pasta. (Optional: Sprinkle with cheese, black pepper or hot red-pepper flakes.) Refrigerate or freeze remaining sauce for another meal. Makes 4 cups.
