Peel tomatoes by scoring the skin of each tomato with a sharp knife (do not cut too deep). Then, place scored tomatoes into a pot of boiling water and boil for approximately 1 to 1 1/2 minutes. Remove tomatoes and plunge into cold water. Peel and dice tomatoes and set aside.
Heat olive oil in a saucepan. When hot, add garlic and crushed red pepper. Saute until garlic turns slightly golden. Add chopped onion and saute an additional 2 1/2 minutes.
Add chopped plum tomatoes and cook approximately 5 minutes. Add salt to taste. Add chopped parsley and extra virgin olive oil if desired, just before using.