Preheat oven to 200°C. Combine ¼ cup (60ml) of the oil with the Moroccan spice mix, garlic, lemon rind and 1 tbs of the lemon juice in a small jug. Place lamb in a glass or ceramic dish. Pour over marinade and set aside for 10 mins to develop the flavours.
Line a baking tray with baking paper. Place the capsicum, pumpkin and onion on the lined tray. Drizzle with remaining 1 tbs oil. Roast for 30 mins or until golden and tender.
Meanwhile, heat a frying pan over medium-high heat. Cook the lamb for 5 mins or until browned all over. Place the lamb on a rack in a roasting pan. Roast for 20 mins for medium-rare or until cooked to your liking. Set aside for 15 mins to rest. Thickly slice.
While the lamb is resting, place the couscous in a large bowl. Pour over 1½ cups (375ml) boiling water. Cover and set aside for 5 mins. Use a fork to separate the grains.
Add the roasted vegetables and chickpeas to the couscous. Whisk the extra oil and remaining lemon juice in a small jug. Pour over the couscous salad and toss to combine.
Arrange the couscous salad on a platter. Top with sliced lamb, pine nuts, mint and coriander.