Place chiles on a tray under the broiler, directly on the grill, or directly over the open flame. I prefer to broil them. Whatever method you choose, turn them every 2 to 3 minutes for a total of 6 to 9 minutes. They must seem charred and blistered on the outside, while the flesh must be cooked but not burnt. Place them immediately in a plastic bag, close it tightly and let them sweat for 10 to 20 minutes. Lastly, under a thin stream of cold water, remove the charred skin, which should come right off. Make a slit down one side of the pepper and remove the cluster of seeds and veins. Once cleaned, pat them dry.