01 - Set oven to 320°F for slow roasting.
02 - Pat the lamb shoulder completely dry with paper towels. Generously season all sides with salt and freshly ground black pepper.
03 - Combine garlic cloves, rosemary, thyme, oregano, lemon zest, and olive oil in a food processor. Pulse until a coarse paste forms.
04 - Rub the herb and garlic paste thoroughly over the entire lamb shoulder. Press the paste firmly into the meat to ensure adhesion.
05 - Heat 1 tablespoon olive oil in a large roasting pan or Dutch oven over medium-high heat. Sear the lamb shoulder on all sides until deeply browned, approximately 5-7 minutes total.
06 - Remove the lamb and set aside. Arrange the sliced onions, carrot chunks, and celery pieces evenly across the bottom of the roasting pan. Place the seared lamb on top of the vegetables.
07 - Pour the white wine and stock around the base of the lamb, avoiding pouring directly over the herb-crusted meat.
08 - Cover the roasting pan tightly with aluminum foil or a secure lid. Transfer to the preheated oven and cook for 4 hours. Baste the lamb with pan juices every hour.
09 - Remove the cover and continue cooking for an additional 30 minutes to allow the exterior to develop a rich, caramelized color.
10 - Remove the lamb from the oven. Let rest loosely covered for 20 minutes before serving. This allows the juices to redistribute throughout the meat.
11 - Skim excess fat from the pan juices. Serve the lamb alongside the roasted vegetables with the defatted cooking sauce.