01 - Preheat your oven to 325°F.
02 - In a small bowl, combine garlic, rosemary, thyme, oregano, lemon zest, lemon juice, olive oil, salt, and pepper. Mix thoroughly to create a uniform paste.
03 - Pat the lamb shoulder completely dry with paper towels. Rub the marinade generously over all surfaces, working the mixture into any crevices and under the fat layer.
04 - Arrange the carrots, onions, and celery in an even layer at the bottom of a large roasting pan. Place the seasoned lamb shoulder directly on top of the vegetable bed.
05 - Pour the white wine and broth into the pan around the base of the lamb, avoiding pouring directly over the seasoned meat.
06 - Cover the roasting pan tightly with aluminum foil or a fitted lid. Roast in the preheated oven for 2.5 hours.
07 - Remove the foil and increase oven temperature to 400°F. Return the lamb to the oven and roast uncovered for 30 minutes, or until the exterior develops a deep golden-brown color and the meat pulls away easily from the bone.
08 - Transfer the lamb to a serving platter and cover loosely with foil. Allow the meat to rest for 15 minutes before carving to redistribute juices throughout the meat.
09 - Skim any excess fat from the surface of the pan juices. Serve the carved lamb alongside the roasted vegetables, passing the defatted pan sauce separately.