General tips
Tie each shank with butcher's twine before bagging. The marrow at the center of the bone wants to slide out during a long 24–36 h bath, and the twine holds the meat against the bone where it belongs. Without twine, you'll be fishing pieces out of the bag.
Sear hard before bagging - that's where the flavor lives. Veal shanks have less natural fat than beef so the Maillard browning carries the dish. Use a heavy pot, plenty of oil, and don't crowd the pan. Brown all sides, including the cut faces.
Cook at 165°–170°F for 24–36 h. Veal collagen melts more slowly than beef, so don't be tempted to shortcut the time. The meat should be tender enough to cut with a spoon but still hold its shape on the plate.
Build the gremolata while the bath finishes. Lemon zest, garlic, and parsley chopped fine - that's it. The bright, sharp topping is the contrast that keeps the rich braise from being one-note. Sprinkle generously over each shank just before serving.
Anti-tip: don't skip the marrow. That's the prize - the silky, beefy center of every osso buco. Serve it with a tiny spoon and toasted bread for spreading. If you cook this dish and discard the marrow, you've missed the entire point.
Fall-Apart Tender tips
Use cross-cut veal shanks with bone marrow intact
Tie shanks with kitchen twine to hold shape
Gremolata is essential for brightness