For Rub: combine all ingredients and 3g salt flakesin a bowl.
Score lamb at 3cm intervals and rub all over with spice rub. Cover and chill for 2 hours or overnight in refrigerator. Stand at room temperature for 30 minutes before roasting.
Pre-heat grill or barbeque to high on one side and medium on the other. Place lamb on the hot side to get a good char on the lamb. When the internal temperature reaches 40◦C, remove and place on medium side to finish. Cook until internal temperature reaches 56◦C. Remove from heat, rest meat covered loosely with foil.
To make dressing: combine yoghurt, mint, cumin and 3g salt flakesin a bowl.
Place lamb and vegetables on a serving platter, scatter with extra mint and drizzle with some yoghurt and mint dressing.
