There really is no meat that shouldn't be smoked (refer to my avatar line)...where there's a will, there's a way. London Broil is typically from the primal round cut, top round in specific, and is very lean (often found to be cut on the bias, not directly across the grain). Depending on the butcher and meat dept manager, if buying from the supermarket, there may be variations as to where this labeled cut is taken from. Being lean, it should be cooked med-rare to medium, at most. There is a bit of, what some would say, deception, on the label of a London Broil, as it's not the cut so much as the cooking method. London Broil recipes usually call for marinating the beef, then oven broiling or grilling. Nonetheless, you may want to consider a reverse sear, if you wish to smoke it, giving the best of both worlds (smoke flavor and light charring with grill marks). You could also smoke and pan-sear (cast iron does a great job for this). If you have the typical ~2" thickness that I generally find with the London Broil (quite similar to the cross-rib chuck roast), it makes a great subject for slicing thin before serving/plating. These also make good subjects for fajitas with some light trimming prior to cooking, again, providing the beef is not overcooked. Don't forget to rest it for a few minutes after the sear to redistribute those precious juices before slicing.
Eric
