Wipe off dried New Mexico chilies. Lay in single layer in a rimmed pan. Toast in a 350° oven just until chilies begin to get fragrant, 3 to 5 minutes. Let chilies cool, then discard stems and seeds. Put chilies in a bowl and pour 1 quart boiling water over each 1/2 pound chilies (about 36). Let stand until chilies are soft, at least 10 minutes. Whirl chilies and soaking water in a blender until smoothly puréed. Cover and refrigerate up to 3 days, or package airtight and freeze up to 6 months. Thin with water or broth to use.
Nutritional analysis per 1/2 cup.