Like Caesar salad and chicken à la Marengo, Joe's Special was apocryphally invented when a beleaguered chef threw together whatever was left in his larder and served it to his hungry clientele. Another version has it that some Prohibition-era jazzmen stormed New Joe's on Columbus and demanded a high-protein snack after a full night of jamming. In any case, this simple, hearty dish has become as synonymous with the whole Joe's hypothesis as grilled steaks, open kitchens, and Italian accents. Original Joe's has upheld the tradition since 1937, and its Joe's Special is worth imitating. Sit at the counter and enjoy the show as one of the unflappable range chefs sautés coarsely ground, house-butchered chuck with shards of onion and a bushel of deep-green spinach, breaks in an egg, stirs up the whole mess, and serves you the result. Like many simple creations, a good Joe's Special is a deeply rewarding thing: earthy, juicy, and purely elemental. Order it with sautéed mushrooms on the side to add another dimension.