When your recipe only calls for a few tablespoons of tomato paste (or pesto or chipotles in adobo) don’t worry about the rest of the can going bad. Instead, measure out the leftovers by table spoons and freeze the portions in an ice cube tray. Once they are solid, pop them out and store in a plastic bag. Then the next time you need tomato paste, no need to thaw just add the frozen portion to your recipe.
Have you ever frozen tomato paste?