1. Heat oil in a large stockpot over medium heat. Add shallots and garlic and cook, stirring, until softened, 6 to 8 minutes. Add tomatoes, oregano, salt, black pepper, crushed red pepper flakes, and 1/2 cup water.

2. Increase heat and cook for 30 minutes, stirring occasionally and breaking up tomatoes slightly with a wooden spoon. Reduce heat to medium and simmer 30 to 45 minutes. Use immediately or remove sauce from heat and let cool completely. Cooled sauce may be kept frozen in an airtight container for up to 3 months.