After peeling the tomatoes, you can freeze them. (Actually, you can also freeze them before peeling). Since tomatoes have a high water content, place them in a strainer or colander after chopping to drain as much water as possible before freezing. To freeze, place the tomatoes on a parchment paper-lined baking sheet in the freezer. When frozen (about 3 hours) move them to an airtight container, leaving some room for expansion. While they may become slightly mushy when defrosted, they’ll still work perfectly for sauces and soups.