6In some recipes you can use the chiles once they have been re-hydrated. You can chop them up and add them as desired. You will most likely need one more step though. In the old days, rehydrated chiles were ground up using stone tools and then added to the dish. With modern conveniences we can do this with a blender. (A food processor will do a reasonable job, but may not get it as smooth as necessary. I have a mini-food processor that has a smaller blade and does the job as well as a blender, and it's easier to clean.)
You will need to add some liquid to the chiles to blend them properly. The liquid will depend on what you're making. For general use, plain water is fine. Or if it is not bitter, you can use some of the soaking liquid. If you are making a sauce with vinegar in it, use a portion of the vinegar from the recipe.
Blend or process the chiles and liquid into a paste and use as needed. It is also convenient to add your seasoning to the chile paste. Throw a couple of garlic cloves in and you can avoid having to chop the garlic separately.