Most recipes call for only a small portion of tomato paste -- you use a tablespoon or two, and the rest invariably goes to waste. To save the remainder: Carefully open both ends of the can with a can opener. Remove one metal end, and discard it. Leave the other in place. Wrap the entire can in plastic wrap, and freeze overnight. The next day, use the metal end to push the frozen paste out the open end. Discard can, tightly rewrap unused portion, and store in freezer up to 3 months, slicing off just as much as you need each time you cook.