Milan, Lombardia — ossobuco is documented in Milanese culinary sources from the 19th century. The pairing with risotto alla Milanese (saffron risotto) is canonical in Milan: the two preparations are served together as a single dish at Milanese restaurants.
Ossobuco (bone with a hole — the marrow cavity in the centre of the veal shin cross-cut) is the definitive Milanese braised preparation: thick cross-cuts of veal shin braised slowly in white wine with mirepoix, tomato (optional in the ancient version — Milanese tradition predates the tomato; modern versions include it), and finished with gremolata — a mixture of finely chopped lemon zest, garlic, and flat-leaf parsley applied raw to the hot ossobuco at the very last moment. The gremolata is not optional; it is the preparation's defining finishing touch, transforming a rich winter braise into something vivid and aromatic. The marrow inside the bone is considered the prize.
Ossobuco alla Milanese at the table, gremolata scattered over — the braising sauce rich and slightly sticky; the meat falling from the bone in tender pieces; the bone sitting in the centre with its precious marrow. The gremolata, added raw, provides an immediate burst of fresh lemon, garlic, and parsley that cuts through the richness. The marrow spread on bread alongside is the luxury within the luxury.
Tie each ossobuco round with kitchen twine around the circumference (prevents the meat from collapsing away from the bone during braising). Dust lightly with flour; brown deeply on both sides in butter and oil. Remove; cook mirepoix (onion, carrot, celery, garlic) until softened; add white wine; reduce. Add ossobuco; add tomato (optional, just a tablespoon of tomato paste for colour) and enough broth to come halfway up the pieces. Braise covered at very low heat 1.5-2 hours until the meat is completely tender and yielding. Make gremolata: very finely mince lemon zest, garlic, and flat-leaf parsley together. Apply gremolata directly to each ossobuco when plating — not before, not to the sauce.
The marrow in the bone hole is the most prized element — a special thin spoon (a marrow spoon or a small teaspoon) is used to extract it; the marrow spread on the contorno bread is the cook's reward. Ossobuco is traditionally served with risotto alla Milanese (the saffron risotto) — the pairing is canonical. The gremolata is also sometimes varied with orange zest added alongside the lemon.
Braising liquid covering more than halfway — the ossobuco should braise in a relatively small amount of liquid, not swim; the concentrated braising juices are the sauce. Not tying the pieces — without the twine, the meat shrinks away from the bone and the presentation is lost. Adding gremolata before service or to the sauce — the gremolata must retain its raw, fresh character; cooking destroys its aromatic oils.
Marcella Hazan, Essentials of Classic Italian Cooking; Giorgio Locatelli, Made in Italy