Tomato paste is just a concentrated tomato sauce. You cannot directly substitute tomato paste for tomato sauce. However, if you don’t have tomato sauce but you have canned tomato paste, you can make a tomato sauce substitute very easily.
How to Make Tomato Sauce from Tomato Paste
All you have to do to turn tomato paste into tomato sauce is add one cup of water to 3/4 cup of tomato paste. Of course, you can add more tomato paste or less water if you want a stronger tomato sauce.
How Do I Store Leftover Tomato Paste from a Can?
Isn’t it a pain when you need just a tablespoon of tomato paste from a can and you have most of the can left over after you’re done cooking? Well, you can, of course, store it in the freezer by putting it into ice cube trays, but it does not come out very easily. However, for long term storage, this will work well. Just freeze it into cubes and, after it is frozen, pry out the cubes carefully and store in plastic bags. Take out just enough to use as you need it. This is a good way to store tomato paste, but it’s a little much for just a little bit left over from the can.

Another handy tip is to keep in mind the tomato sauce substitute from above. Many recipes call for a combination of tomato sauce and a little tomato paste. You can use the left-over tomato paste to make some, or all of the tomato sauce for the recipe, rather than buying separate tomato sauce. And, if you make your tomato sauce stronger, with more tomato paste for the amount of water you use, you may as well just do away with the “paste” part of the recipe altogether.
Buy Tomato Paste in a Tube Instead of a Can
Regardless, canned tomato paste is a bother, if you ask me. I don’t buy it. Instead, I keep a tube of Amore double-concentrated tomato paste, or other brand in the fridge. It lasts a very long time, although I can’t say for sure how long. Since it is double-concentrated, you can use less of it, and you only need to squeeze out just the amount you need, leaving the rest safely stored in the tube. If you want to make tomato sauce from tubed tomato paste, use less tomato paste for the same amount of water. Start with about half the amount of tomato paste as for canned tomato paste, and adjust until you get the consistency and concentration you want.
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