Best roast leg of lamb

INGREDIENTS

• 1 bulb garlic, 3 cloves peeled and crushed, the others left whole
• 1 small bunch fresh rosemary, half the leaves removed and coarsely chopped, half in sprigs
• zest of 1 lemon
• olive oil
• 2 kg quality leg of lamb
• sea salt
• freshly ground black pepper
• 1.5 kg potatoes, peeled and cut in half
• 4 tablespoons chopped fresh mint leaves
• 1 teaspoon sugar
• 2 pinches salt
• 1 tablespoon hot water
• 3 tablespoons wine vinegar