Quarter peppers lengthwise, discarding stems, seeds, and ribs. Put peppers, skin sides up, on rack of a broiler pan and broil about 2 inches from heat until skins are blistered and charred, 8 to 12 minutes.
Transfer peppers to a bowl and let stand, covered, until cool enough to handle. Peel peppers.
Lay whole peppers, on their sides, on racks of burners (preferably 1 to a burner) and turn flame on high. Char peppers, turning them with tongs, until skins are blackened, 6 to 8 minutes.
Transfer peppers to a bowl and let stand, covered, until cool enough to handle. Peel peppers. Cut off tops and discard seeds and ribs.
