Lamb shanks are collagen-rich, bone-in cuts that reward patience. They need sustained gentle heat to transform from tough and sinewy into the spoon-tender, fall-off-the-bone texture that makes them a restaurant centerpiece. Sous vide gives you that braised result without the oven-watching, liquid-level-checking, and turning that traditional braising requires. Bag the shanks with aromatics, set the temperature, and walk away for 18–24 h. At 170°–175°F the collagen fully converts to gelatin over 18–24 h, producing classic braise-style texture where the meat slides off the bone with a nudge. At 180°–185°F the collagen melts completely for a shreddable, ragu-ready texture. The bag juices from lamb shanks are some of the richest cooking liquids you will ever produce. They gel when chilled because of the dissolved collagen, and they reduce into a glossy, body-rich sauce that flour-thickened gravies cannot match. Always sear the shanks after the bath, not before. The long cook washes away any pre-sear crust. A quick 30-second sear while the shank is still hot builds a fresh, burnished exterior. This guide focuses on timing for fall-apart texture and finishing steps for glossy sauces and crisped edges.