Osso buco is a dish that understands the value of time. Veal shanks start out sturdy and rather stern, then slowly surrender to a low braise until the meat turns spoon-tender and the marrow softens inside the bone. By then the sauce has become something more than broth, less than gravy, and exactly what you want spooned over risotto or polenta.
The dish would risk heaviness if not for the finish. A little lemon zest, parsley, and garlic scattered over the top brings the whole pot back into focus. That last-minute brightness is what keeps osso buco elegant rather than merely rich, and it is part of why the classic has lasted.