In a large stockpot, heat oil over moderate heat and saute onions, pepper and garlic until tender, about 8 minutes.
Add tomato puree, sugar, salt, oregano, basil and bay leaves. Bring to a boil then simmer, uncovered, about 60 minutes. If sauce is not thick enough, add tomato paste and summer, uncovered, for 30 additional minutes.
Jar the sauce following canning directions and process quarts for 30 minutes. If salt must be omitted, add 1/2 teaspoon citric acid to each quart jar. Makes 7 quarts. Enjoy!