1.Preheat oven to 180°C/350°F.
2.Rub lamb with half the harissa; drizzle with half the oil. Season. Cook lamb on heated grill plate (or grill or barbecue) over medium-low heat, covered with a sheet of foil, for 4 minutes each side for medium or until done as desired. Remove lamb from heat; cover with foil, rest for 5 minutes.
3.Meanwhile, enclose barley wraps in foil; heat in oven 5 minutes.
4.For red salad, place cabbage, beetroot, onion and radish in a large bowl with juice, garlic and remaining oil; toss gently to combine. Season to taste.
5.Swirl remaining harissa through yoghurt.
6.Slice lamb thinly. Divide lamb, red salad, yoghurt mixture and herbs among wraps; roll up to serve.
We used a milder harissa rather than the much hotter Tunisian one available in a tube. If using harissa in a tube, start with 1 teaspoon and add more to taste.Note