01 - Preheat the oven to 320°F.
02 - Pat the lamb shoulder dry, then make small incisions all over and insert garlic halves into each cut.
03 - Combine rosemary, thyme, oregano, lemon zest, sea salt, black pepper, and smoked paprika; rub this mixture evenly over the lamb, pressing into the incisions.
04 - Heat olive oil in a large roasting pan over medium-high heat and sear the lamb on all sides until golden brown, about 5 to 7 minutes. Remove and set aside.
05 - Scatter onions, carrots, and celery in the bottom of the roasting pan and place the seared lamb on top of the vegetables.
06 - Pour the white wine and stock around the lamb (not over it) and cover tightly with foil or a lid.
07 - Roast in the oven for 3.5 to 4 hours, basting once or twice, until the meat is very tender and easily pulls away from the bone.
08 - Remove the cover and continue roasting uncovered for the final 30 minutes to brown the lamb.
09 - Let the lamb rest, tented with foil, for 15 minutes before carving. Serve with the roasted vegetables and pan juices.