Basic Tomato Sauce

Heat oil in a large heavy pan or Dutch oven over medium-low heat. Add onion and cook, stirring often, until softened, about 5 minutes. Add garlic and crushed red pepper; cook for 30 to 60 seconds. Add tomatoes, tomato paste and oregano; mash with a potato masher. Bring to a boil. Simmer, uncovered, over low heat, stirring frequently, until the tomatoes cook down to a thick mass, 45 to 55 minutes. Season with pepper.