In a large skillet or saucepan, heat the extra-virgin olive oil and unsalted butter over medium heat. Once the butter is melted and bubbling, add the finely diced onion. Sauté for about 5-7 minutes until the onion is translucent and fragrant.
Stir in the minced garlic and cook for another minute until it becomes fragrant. Be careful not to burn it! Next, add the dried oregano, crushed red pepper flakes, and dried basil. Stir well to combine and let the spices toast for about 30 seconds.
Pour in the 28 ounces of crushed tomatoes. Stir everything together, ensuring that the spices are evenly distributed throughout the sauce.
Add salt and pepper to taste. Remember, you can always add more later, so start with a pinch and adjust as needed.
Bring the sauce to a gentle simmer. Let it cook for about 15-20 minutes, stirring occasionally. This will allow the flavors to meld beautifully. You’ll know it’s ready when the sauce thickens slightly and the aroma fills your kitchen.