Originally served without benefit of bun or bread, it might more accurately have been called a Salisbury steak, seasoned as it was with celery, nutmeg, and worcestershire sauce, in a thick brown gravy. That's the way the '21' burger came to the table for nearly four decades, until the chef Alain Sailhac and the chef-restaurateur Anne Rozenzweig took over in 1986. The duo ditched the old-fashioned seasonings and tucked a big pat of herb butter inside the patty; the butter both flavored the meat and kept it tender and juicy. Problem was, loyalists did not want a better burger; they wanted the same old mound of meat they were used to. So, when Michael Lomonaco became chef in 1988, he restored order, but just: he served the burger open-face atop a grilled, thyme-scented bruschetta. The current incarnation harks back to the burger's roots, with minced onion, spices like coriander and fennel seeds, fresh herbs, and even duck fat, only nowadays it's served on a bun—a puffy brioche that, while delicious, makes the whole thing too big and awkward to eat out of hand. Some burgers, we suppose, are meant to be tackled with a knife and fork.