1-First, preheat the oven to 240°C (465°F) or 220°C if using a fan. Rub the 1.8 kg bone-in lamb shoulder with 2 tbsp olive oil, 2 tsp salt, and 1 tsp black pepper for that flavorful crust.

2-Next, make about 12 deep incisions in the lamb without going all the way through, and insert the rosemary sprigs and sliced garlic slivers. This step infuses the meat with amazing flavors as it cooks.

3-Then, place the quartered onion, halved garlic head, and a few rosemary sprigs in the base of your roasting pan. Set the lamb on top and pour 1 cup water around it. Cover the pan tightly with a lid or double-layer foil to lock in moisture.

4-Put the lamb in the oven and immediately reduce the temperature to 180°C (350°F) or 160°C for fan ovens. Roast it covered for 3 hours, letting the slow process work its magic.

5-After that, remove the foil and check the liquid; add about 3/4 cup water if it’s low. Crank up the oven to 220°C (425°F) and roast uncovered for 20-30 minutes to get that crispy skin. Check if the meat pulls apart easily with forks; if not, cover and return to 180°C until it’s tender.

6-Once done, let the lamb rest loosely covered with foil and towels for at least 20 minutes. Meanwhile, prepare the gravy by removing most of the fat from the pan, adding 2 tbsp flour, and cooking it briefly. Gradually stir in 2 cups beef broth or the wine-water mix, mash the onion and garlic, simmer for 1-2 minutes, season, strain, and serve alongside the lamb.