Skewer chile peppers and sear over an open flame, 6" to 10" from heat. Turn chilies, until blistered all over (if not removing skin) or until slightly burned, but not blackened (if removing skin), about 8 minutes. Or place chilies on a grilling rack or baking sheet and broil in oven 4" from heat for about 8 minutes.
If removing skin, place chilies in an airtight container or paper bag. Seal and let sweat for 20 minutes. When cool enough to handle, remove chilies one by one and slip off skins or peel with a paring knife.
To prepare chilies for stuffing: Roast and peel chile peppers as directed above. Cut a circle around the stem and detach the core with the seeds.
Carefully scrape out any remaining seeds.
To remove some of the heat from a chile pepper: Wash the chile and cut it lengthwise. Remove the seeds and ribs, where heat-producing capsium is most concentrated.
Soak the chile flesh in an equal mixture of cold water and vinegar before using.