Wash and core tomatoes. Cut out anything undesirable. Process in blender or food processor. No peeling necessary. Bring to boil and simmer 15 minutes. Longer if you want the puree thicker. Ladle into prepared jars leaving 1/4-inch head space. Add lemon juice (1 T. per pint, 2 T. per quart) or citric acid. Wipe rims. Place prepared lids on jars. Screw on bands. Water bath for 45 min.
One quart is about 28 oz which is what a lot of recipes call for. It can be used to make soup, sauce, pizza sauce, BBQ sauce, salsa, or anything.