Stewed tomatoes are tomatoes that have been peeled and cooked. Use stewed tomatoes as a base for other recipes. They can be made into marinara sauce or stirred into soups or chili. Stewed tomatoes contain all the nutritional value of fresh tomatoes, including vitamin C and lycopene, a powerful antioxidant and cancer fighter.

Bring 4 or 5 inches of water to a boil in a large pot. Drop a few tomatoes at a time into the boiling water. Let them boil for 30 seconds. Remove them from the water with the slotted spoon. Drop them into a large bowl of ice water to cool. Peel the tomatoes using the paring knife. The hot water loosens the skin to make them easier to peel.

Heat the oil in a saucepan. Saute the chopped onions, green peppers and celery in the hot oil until the onions become translucent. If you like your stewed tomatoes without additional vegetables, skip this entire step.

Remove the stem end and quarter the tomatoes. If you don't like seeds in your stewed tomatoes, remove the seeds.

Add the tomatoes to the saucepan. Cook them over low heat until they begin to give off some juice, then raise the heat to medium. Cook the tomatoes until they are tender, typically 10 to 20 minutes if you like tomato chunks in a loose sauce. Let them cook for as long as 45 minutes if you like them cooked down almost to a marinara. Stir the sauce frequently and monitor the temperature so the tomatoes don't stick or burn.