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.
Carefully scrape out any remaining seeds.
Soak the chile flesh in an equal mixture of cold water and vinegar before using.