The fajita recipe–you know, the one that involves laying pieces of meat right on the hot coals–works brilliantly, though there is definitely a leap of faith involved the first time around. A word to the wise, though–flank steak is often somewhat thicker than the skirt steak that he recommends, so be prepared to adjust cooking time a bit.
Oh, and you probably only really want to consider this with real hardwood charcoal, not any of that processed, compressed stuff.