Cooking tomatoes briefly and then straining them creates a thick liquid known as tomato puree. By cooking tomatoes for a longer period and further reducing the liquids, a thicker, richer tomato paste is created. Neither tomato puree nor tomato paste has any seasonings added. Preparing your own tomato puree from tomato paste is a process that takes just a few steps and allows you to substitute tomato paste in recipes that call for tomato puree.
Place 2 tbsp. of tomato paste in a measuring cup.
Add water to make one cup.
Place the water and tomato paste in a saucepan.
Whisk the tomato paste and water together in the saucepan, breaking up thick clumps of paste, until you have a smooth puree.