01 - Preheat oven to 325°F.
02 - Pat the lamb shoulder dry and season generously with salt and pepper.
03 - Heat olive oil in a large Dutch oven over medium-high heat. Brown the lamb on all sides, about 3–4 minutes per side. Transfer lamb to a plate.
04 - Add onion, carrots, celery, and garlic to the pot. Sauté for 5 minutes, scraping up browned bits.
05 - Stir in rosemary, thyme, and bay leaves. Add tomato paste and cook for 1 minute.
06 - Pour in red wine; simmer for 2–3 minutes. Add stock and bring to a simmer.
07 - Return lamb to the pot, nestling it among the vegetables. Cover tightly with a lid. Transfer to the oven and braise for 2 hours, basting occasionally.
08 - Whisk together molasses, Dijon mustard, apple cider vinegar, and brown sugar to make the glaze.
09 - After 2 hours, uncover the lamb and increase oven temperature to 400°F. Brush lamb with glaze. Roast uncovered for 30–40 minutes, basting twice more with glaze, until lamb is deeply caramelized and tender.
10 - Remove lamb from pot and let rest for 10 minutes before slicing. Strain and reduce pan juices if desired to serve alongside.