Remove any excess fat from the lamb. Using the point of a sharp knife, make deep slits all over the leg. Place the lamb in a large non-reactive dish.
In a small bowl, combine all the ingredients. Rub over the lamb, pressing it into the slits.
Yogurt mixture In a food processor or blender thoroughly blend the yogurt, nuts, and turmeric. Spread over the lamb. Drizzle the honey over the lamb, cover, and marinate for 1 day in the refrigerator, turning occasionally. Preheat the oven to 450 degrees.
Transfer the lamb to a roasting pan, cover (aluminum foil is fine), and cook for 30 minutes. Reduce the oven temperature to 350 degrees and cook for 1 3/4 hours more, or until meltingly tender. Uncover and serve warm or at room temperature.