Coat each pepper in a little oil. Iif you have gas burners, you can roast a pepper directly on the grate over high heat, turning the pepper occasionally until it’s charred all over.
To char a batch of peppers, a hot charcoal or gas grill is best, but the broiler works, too. Put the oiled peppers on a foil-lined baking sheet and broil as close to the element as possible, turning them so they char evenly.
For electric stoves, get a stovetop pepper roaster. It turns your electric burner into a little grill, and it’s also handy for heating tortillas. Sur La Table sells a stovetop pepper roaster for $14.99.