In a large skillet set at medium-high, saute ⅓ cup diced onion and 2 Tablespoons minced garlic in 1 Tablespoon olive oil. Add in a handful chopped fresh basil leaves, stir and let cook for a few minutes, until onions are translucent.
Turn heat down to medium-low and add 1 28oz can crushed tomatoes and season with salt, pepper and oregano to taste.
Stir in another 2-3 Tablespoons of olive oil and let simmer on low for a minimum of 20 minutes.