* In Bulgaria we (used to) have a tradition of preserving food for the winter. One of the typical things was sterilised tomato juice, prepared of ground tomatoes, salt, and some parsley (optional). Some black pepper may be added, too. The juice was then poured into glass bottles and sterilised for several minutes. Prepared this way it is ready to be added to soups and stews. Alternatively, you could drink it just as is, like any other juice.
If you do not have such home-made tomato juice or home-canned tomatoes, you could use canned tomatoes from the supermarket. All you need to do is emulsify them with an immersion blender till smooth and liquid.