Cut the lamb into 2.5 cm (1 in) dice. Whisk together the ras el hanout and vegetable oil and marinate the lamb for at least 1 hour or overnight if possible.
Thread the meat on to metal or presoaked wooden skewers, putting about 6 pieces of lamb on each one.
Meanwhile, put the couscous in a bowl, add the hot chicken stock, cover and allow to stand. Chop the coriander, reserving some leaves for garnish. Remove and finely chop the peel from the preserved lemons and chop the apricots. Add the preserved lemon to the cooked couscous with the coriander, apricots and currants, season with salt and pepper and mix lightly.
Make the dressing by mixing all the ingredients in a small bowl. Set aside.
Cook the lamb skewers on a preheated hot griddle pan for 3—4 minutes each side until cooked through. Spoon the couscous on to serving plates and top each with 2—3 skewers and some yogurt dressing.