Heat 1 tablespoon olive oil over medium heat in a saucepan. Add the onion and garlic and cook gently for 5 minutes, until softened and fragrant. Add the tomatoes and remaining 3 tablespoons olive oil and bring to a simmer. Cover and simmer for 30 minutes, stirring often.
Transfer to a blender and blend until smooth. Add the salt, sugar, oregano and basil and blend until combined.
Return to the saucepan and simmer partially covered until thickened to the desired consistency, 15 to 30 minutes. Taste and adjust salt as desired. (Variations: Stir in red pepper flakes, a splash of cream, grated Parmesan cheese, or a splash of balsamic vinegar if desired.)
Serve 2 cups tomato sauce with 8 ounces pasta, and top with Parmesan cheese, Pecorino Romano cheese, and/or red pepper flakes. Sauce stores refrigerated for 5 days or frozen for 3 months.