Preheat oven to 200°C. Line a roasting pan with baking paper. Season lamb with salt and pepper and bake for 1 hour and 15 minutes.
Meanwhile, in a small bowl, combine macadamia, rosemary, honey and balsamic glaze. Set aside.
To make the mint sauce, coarsely chop mint and parsley and combine with garlic and zest in a bowl. Stir in vinegar and enough oil to form a slightly thick sauce. Set aside.
Remove lamb from oven and reduce oven temperature to 180°C. Press macadamia mixture firmly over lamb. Return to oven and bake for 45 minutes or until crust is golden.
Remove lamb from oven and cover loosely with foil. Rest for 10 minutes before carving. Serve with rustic mint sauce.
