1-Preheat the oven to 240°C (465°F) or 220°C (fan forced 425°F). Rub the lamb shoulder with 2 tablespoons olive oil, 2 teaspoons salt, and 1 teaspoon black pepper for even flavor.

2-Make 12 deep incisions in the lamb without piercing through and stuff them with 3 garlic cloves cut into slivers and 8 sprigs rosemary to infuse the meat.

3-Place the quartered onion, halved garlic head, and some rosemary in the base of a roasting pan, then put the lamb on top and pour 1 cup of water around it.

4-Cover the pan with a lid or double layer of foil and reduce the oven temperature to 180°C (350°F) or 160°C fan. Slow roast covered for 3 hours to achieve tenderness.

5-Remove the foil, check for liquid and add 3/4 cup water if necessary, then roast uncovered at 220°C (425°F) for 20 to 30 minutes until the skin is browned and crisp.

6-Test tenderness by pulling the meat apart with two forks; if it is not tender, cover and cook longer at 180°C (350°F). Remove the lamb and let it rest covered loosely with foil and towels for at least 20 minutes.

7-For the gravy, remove most fat from the pan, leaving 2 tablespoons. Place the pan over medium-high heat, stir in 2 tablespoons flour, and cook for about 30 seconds. Gradually add 2 cups beef broth (or the wine and water mix), mash the onion and garlic in the pan, and simmer for 1 to 2 minutes until thickened. Season with salt and pepper, strain, and serve with the lamb.