This regional speciality calls for a large roast to be grilled (but not smoked) over intensely hot coals while being flipped constantly to avoind burning. The meat comes off the grill well charred, almost black on the exterior but not burned, and rosy pink in the center, bordering on rare. The meat is sliced thin, piled on kaiser rolls, and top with sliced onions and a horseradish-mayonnaise mixture some locals refer to as "Tiger Sauce". The final result is tender, smoky and spicy. In Baltimore, a deli slicer is often used to shave the meat thinly for sandwiches. It's easiest to cut the roast in half lengthwise before slicing it as thinly as possible. From "The Best of America's Test Kitchen 2010" by Cooks Illustrated.