Lamb stew with spiced couscous

Ingredients

• 1 kg lamb stewing meat (such as lamb chops of leg of lamb)
• 1 grapefruit (zest + juice)
• 3 tablespoons ras el hanout
• 2 tablespoons ground cinnamon
• 2 teaspoons ground ginger
• 2 tablespoons sambal or chili pepper paste
• 3 garlic cloves
• 2 onions
• large handful green olives
• 1 can of tomato chunks
• 300 gram couscous
• olive oil
• pepper and salt to taste
• handful of flat leaf parsley