Chop all tomatoes if using fresh, I just squeeze them with my hands in a large bowl. Chop your garlic, onions and fresh basil if using (set aside the basil I leave it whole). If using canned crush tomatoes, reduce cooking time by 8 mins. (sometimes canned tomatoes have basil and/or tomato puree this is fine.
Heat a large pan or dutch oven (pot) add Extra Virgin Olive Oil and saute the onions until clear, add garlic and cook (3-4 mins) don't burn the garlic.
Add the chopped tomatoes (fresh or canned) and cook for 20 mins on medium flame, stirring every 5 minutes. Add Italian Seasoning, salt & pepper to taste and red pepper flakes and cook for an additional 10 mins add the fresh basil at the end of the cooking. Keep stirring so it doesn't stick to pot.
You can serve with any type of pasta of your choice. Grated Pecorino Romano Cheese or any type your choice. Served with a nice salad and hot garlic or Italian bread.