Kelly's, which was the first place to serve hot roast beef sandwiches on the North Shore, puts together a slightly different sandwich than the smaller shops that dot the area. In the Revere Beach establishment, the beef comes from the steer's knuckle -- the top part of the front leg, or foreshank.
Most other places use top round, from below the steer's rump. The difference is mostly texture, says butcher John Dewar of John Dewar & Co. in Newton and Wellesley. ''The knuckle is softer" than the top round, he says, but ''the top round has a little more chew to it, a little more flavor."
Kelly's knuckle meat is sliced a bit thicker than the meat at other places and piled onto a grilled sesame bun. Other sandwiches are offered on onion buns. And though the beef and the bread might differ, the familiar flavor in all North Shore hot beef sandwiches comes from James River barbecue sauce, a product made in Virginia and used by most of the shop owners.
''We tried to change the sauce once," said Kelly's president Brian McCarthy. ''And people would have none of it. So now we change nothing." -- LEIGH BELANGER