In a medium saucepan over medium-high heat, heat oil until shimmering. Add garlic cloves and sauté until browned, stirring occasionally to prevent scorching, about 3 to 4 minutes. Remove garlic and discard.
Stir in crushed tomatoes, diced tomatoes, sugar (if using), basil, oregano, and salt and pepper to taste (I like 1/2 teaspoon salt and 1/4 teaspoon pepper). Reduce heat to medium and simmer uncovered until flavors have blended, about 10 minutes.
Keep warm over low-heat until serving time, or cool completely and store covered in the refrigerator.
Sugar: This is an optional sauce ingredient; I prefer just 1 teaspoon to balance out the acidity in the canned tomatoes. Sweeten to taste or feel free to omit.
Yield: This recipe makes 4 cups (1 quart) sauce.
Storage: Store leftovers covered in the refrigerator for up to 4 days.
Make ahead: The sauce can be made, cooled, covered, and refrigerated up to 3 days in advance.
Freezer: Cool the finished sauce, then pack into freezer-safe containers (I like to use glass Mason jars; leave a half-inch of head space for expansion), and freeze for up to 3 months.