Medium-high heat for 5–7 minutes, depending on their size. When they are blistered and black all over, place in a plastic or brown paper bag for about 5 minutes to help loosen the skin. When cool enough to handle, peel and scrape off the skin with a small sharp knife, not worrying about getting every last blackened bit. To remove the seeds (necessary in some but not all recipes), first cut off and discard the stems with the attached white core, then slit them lengthwise and scrape out the remaining seeds. For extra heat, leave the membranes intact; for milder heat, cut and scrape them away. In some cases I’ve indicated a slightly different procedure.