It seems like every cook has her own unique way of making marinara sauce. The version below is pretty close to how my Italian grandmother made it. Grandma grew up in a small village on a hill outside Rome, so you know it's authentic.
Marinara sauce is, by definition, meatless. The name "marinara sauce" translates in Italian to "sailor sauce". Legend has it that Italian sailors made this meatless sauce because they couldn't keep meat on their ships for long periods of time, as it would spoil. Their alternative was to dress their pasta with a sauce made from canned tomatoes, olive oil, and aromatic vegetables and herbs that could keep for long periods of time without spoiling.
This recipe is very versatile. If you don't feel like chopping onions, leave them out. If fresh basil is not available, use dried. (Just be sure to reduce the amount of dried basil, using only about 1/3 of the amount of fresh basil you would use, as dried herbs have a much stronger flavor.)
Grandma would make her marinara using tomatoes that she canned from the family garden. Each summer, she would cook, crush, and can enough tomatoes to last us until the following summer. But, living in an apartment without enough sunlight to grow them even on my balcony, I must resort to the canned crushed tomatoes from the store. The result is still delicious.
Some American cooks like to add sugar to tomato sauce. That, Grandma would say, is a sacrilege. While the basil helps to sweeten the sauce, you can add a splash of white wine to sweeten it further. But please don't add sugar if you really want an authentic Roman-style sauce.
Ditto with the oregano, which some people like to add to a marinara. Per Grandma, oregano makes it a pizza sauce. Basil makes it a good marinara.
2 tablespoons extra virgin olive oil
1 clove garlic, minced
1/4 cup chopped onion
1 large can (28 ounces) crushed tomatoes
1/2 tablespoon fresh basil leaves, shredded or coarsely chopped, or 1/2 teaspoon dried basil
Salt and freshly ground black pepper to taste
In a large saucepan or dutch oven, saute the garlic and onions in the olive oil over medium-low heat for 2-3 minutes, until soft and fragrant. Do not let the garlic burn.
Stir in the tomatoes, basil, salt, and pepper. Raise heat to medium high and bring the mixture just to a boil.
Reduce heat to low, cover, and simmer for 20-30 minutes, stirring occasionally.
Use within 2-3 days, or freeze for future use.
-- Approximately 3 cups of sauce