Spice up canned tomatoes with garlic, onions, and red-pepper flakes for a superb quick tomato sauce.
Heat olive oil in a saucepan over medium heat. Add the chopped onion, stirring so that it does not brown, until soft and fragrant, 3 to 4 minutes. Add garlic, and cook, stirring another minute.
Add crushed tomatoes and their liquid. Season with salt, pepper, and red-pepper flakes. Add 2 cups cold water. Bring to a boil, reduce heat, and simmer until sauce has reduced and thickened and has a deep, rich tomato flavor, about 20 minutes. Stir in basil just before serving.