Wash, blanch, skin and core your tomatoes. To blanch, bring a large pot of water to a rolling boil while you prepare a bowl of ice water. Add the tomatoes to the boiling water and cook briefly, usually one to three minutes depending on the size. Remove the tomatoes right away and transfer them to the ice water to stop the cooking. Once cooled, drain well and pat dry. You should have roughly 14 cups of skinned, cored and diced tomatoes. Pro Tip: You can freeze the tomatoes ahead of time. When thawed, the skins will fall right off.