Heat oil in a Dutch oven or large pot. Add the onion and cook over medium heat until soft and translucent, about 10 minutes.Add the garlic, stir, and cook for an additional minute.Add the tomatoes, oregano, basil, sugar, salt and pepper. Stir and bring to a boil.Reduce heat and simmer sauce, stirring occasionally for 30 minutes.For a smoother sauce, place in a food processor or blender and process until you reach your desired consistency.Use immediately or store in the refrigerator for up to 5 days, or freeze for up to a month.