Add the tomatoes, onion, garlic, and olive oil to a large, heavy-bottom pot. Wider base pots work best to allow for stirring and keeping the tomatoes from scorching on the bottom of the pan.

Cook over medium-low heat for 1-2 hours, mashing with a wooden spoon or potato masher occasionally. The sauce should not come above a low simmer.

Once all of the tomatoes, onions and garlic have broken down, turn off the heat and pass the mixture through a food mill (in batches), into a large bowl. Once all the sauce has been passed through, wash out the pot and return the strained tomato sauce to the pot over medium heat. Discard any of the solids.

Cook over medium heat until the sauce reaches desired thickness. Turn off the heat, season with Hey Old Sport Overachiever (or salt) and add the basil. Stir gently and either use or store for later use. Canning preferred for longterm storage (up to 6 months).