1.To make the coriander yoghurt: Combine all ingredients in a small bowl.
2.Thread fish onto four skewers; sprinkle seasoning all over skewers. Cook skewers on a heated, oiled grill plate (or grill or barbecue) for about 3-5 minutes each side or until fish is cooked.
3.Meanwhile, in a large heatproof bowl, combine couscous with the water, cover; stand for about 5 minutes or until liquid is absorbed; fluffing with a fork occasionally. Stir in orange, parsley and spinach; season to taste.
4.Serve skewers with couscous salad and yoghurt.
Soak wooden skewers in water for at least 1 hour to prevent them burning during cooking. We used ling for this recipe but you can use any firm white fish fillets.