Put 2 tablespoons extra virgin olive oil and ½ cup finely chopped onion in a large saucepan or Dutch oven and place over medium-low heat. Stir in a pinch of salt to encourage the onion to release liquid.
Cover the pan and cook gently until softened, 5-7 minutes — the steam created in the covered pot helps this process go a bit quicker. Stir in 2-3 finely chopped or grated garlic cloves and cook a few seconds, until fragrant. If using crushed red pepper, stir it in.
Stir in 2 28-ounce cans whole peeled tomatoes, 1-½ teaspoons salt, pepper and sugar (if using) to the pot. Bring to a simmer. Cook 15-20 minutes. The sauce will bubble up as it simmers. Partially cover the pot to keep it from splashing on your cooktop.
Taste the sauce for seasoning (I usually add about another ½ teaspoon of salt) and stir in the basil.
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Notes
The sauce keeps refrigerated up to one week and frozen up to 2 months in leakproof containers.
If you prefer a smoother sauce, swap out the tomatoes for finely chopped tomatoes or tomato puree. You can also use a handheld stick blender to create your desired consistency.
Optional seasonings: Add about 1 teaspoon dried oregano and crushed red pepper to taste for that classic Italian restaurant aroma and zest. Butter isn't traditional, but it adds a rich flavor. Stir in a tablespoon or two into the hot sauce until it melts.