Steps
1. Preheat oven to 160°C (320°F).
2. Season the lamb shank with salt and pepper.
3. Heat olive oil in an oven-safe pot over medium-high heat. Brown the lamb shank on all sides, about 5 minutes.
4. Remove the lamb and set aside. In the same pot, sauté onion, carrot, celery, and garlic until softened.
5. Add rosemary, red wine, and stock. Bring to a simmer.
6. Return the lamb shank to the pot, cover with a lid, and place in the oven.
7. Braise for 2.5 to 3 hours, until the meat is tender and easily pulls away from the bone.
8. Remove lamb, strain the sauce, and reduce on the stove if desired.
9. Serve the lamb shank with the sauce spooned over.