Preheat a covered barbecue on medium. (Alternatively, preheat oven to 180C.)
Place the lamb in a deep disposable roasting pan. Rub the oil all over the lamb to coat. Season.
Cook in covered barbecue, using indirect heat, for 2 1/2 hours for medium or until cooked to your liking. (Alternatively, cook in oven for 2 1/2 hours for medium or until cooked to your liking.) Cover with foil and set aside for 10 mins to rest.
Meanwhile, cook the potato in a saucepan of boiling water for 15 mins or until just tender, adding the sugar snap peas and snow peas to the pan during the last 2 mins of cooking. Refresh under cold water. Drain. Transfer the potato mixture to a large bowl. Add the spring onion and toss to combine. Season. Transfer to a serving platter.
Place the yoghurt, garlic, mint and coriander in a blender or food processor. Blend or process until smooth.
Serve the lamb with the potato salad and yoghurt mixture.
Serving size: 4
Recipe courtesy of taste.com.au