Preparation Cook onions and garlic in oil in a 4- to 5-quart heavy saucepan over moderately low heat, stirring, until softened, 6 to 8 minutes. Add tomatoes, including juice, and salt, then simmer gently, uncovered, stirring and mashing tomatoes with a fork occasionally, until sauce is thickened and reduced to about 5 cups, 1 to 1 1/4 hours. If sauce tastes too acidic, add sugar and cook 5 minutes more. Cooks' note:• Sauce can be made 5 days ahead and cooled, uncovered, then chilled, covered. • Sauce can be frozen in an airtight container 3 months.
Preparation Cook onions and garlic in oil in a 4- to 5-quart heavy saucepan over moderately low heat, stirring, until softened, 6 to 8 minutes. Add tomatoes, including juice, and salt, then simmer gently, uncovered, stirring and mashing tomatoes with a fork occasionally, until sauce is thickened and reduced to about 5 cups, 1 to 1 1/4 hours. If sauce tastes too acidic, add sugar and cook 5 minutes more. Cooks' note:• Sauce can be made 5 days ahead and cooled, uncovered, then chilled, covered. • Sauce can be frozen in an airtight container 3 months.