You can puree the chopped peppers using a blender and then cook. If all you want to add to your dish is splash of savoriness, grab one of these pantry staples.Neither has the sweetness that tomato paste brings to the party, but when it comes to umami few things compare to fish sauce.Other good substitutes in this vein: Maggi Sauce, Vegemite, anchovy paste, or a smidgen of mushroom soup base. This is the best substitute for those that are allergic to the tomato products. Instructions: From Tomato Puree or Tomato Sauce: Measure out twice as much puree or tomato sauce into a saucepan, and cook down over low/medium-low heat, until thick and reduced by half.Stir regularly to prevent sticking and burning. Tomato sauce can sometimes be used as a tomato paste substitute, although this is often much thinner. If this is used, however, the cook should reduce or eliminate other liquids from the recipe. Fish sauce or Worcestershire sauce. For every tablespoon of tomato paste that’s required, you need to substitute around 2 to 3 tablespoons of tomato sauce. The peppers should be finely chopped. How To Substitute The Tomato Paste With The Red Peppers. If you don’t have time to spare, just use twice as much puree or sauce, and cut the liquids in the recipe by the same amount. Even though tomato sauce is a lot thinner in consistency and has added sugars, it can still be used as an alternative for tomato paste. Some spaghetti sauce or marinara sauce recipes, for instance, call for tomato paste and water. This will help the excess moisture to evaporate.