1Bring a large pot of salted water to a boil. Add the spaghetti and cook according to the package instructions until al dente. Drain and set aside.
While the spaghetti is cooking, finely chop the onion and garlic.
Heat the olive oil in a large pan over medium heat. Add the chopped onion and garlic, and sauté until the onion becomes translucent.
Add the canned tomatoes to the pan, breaking them up with a spoon. Stir in the dried oregano, and season with salt and pepper to taste.
Let the sauce simmer for about 15-20 minutes, stirring occasionally, until it thickens.
Add the cooked spaghetti to the sauce, tossing to coat the pasta evenly.
Serve hot, garnished with additional oregano or fresh basil if desired.