Heat oil in saucepan. Add onions to pan. Add some salt and mix with onions (this will help the onions sweat). Cook gently until translucent. Do not get any color on the onions. Add garlic and cook for a few minutes. Do not get any color on garlic. Add tomatoes and basil. Break up the whole tomatoes as you stir the sauce. Simmer for 45 minutes, stirring occasionally. Season with salt to taste.