Slow-cooked lamb with couscous

Ingredients

• 2 kg lamb shoulder
• 1 butternut squash, deseeded and cut into 1 cm cubes
• 300 ml chicken stock
• 150 g dried prunes
• 300 g couscous
• Small bunch parsley, roughly chopped, plus extra to serve
• Juice of 1 lemon
• 2 tbsp tahini
• 150 g plain yoghurt
• For the marinade:
• 2 tbsp Ras El Hanout
• 3 garlic cloves, peeled and chopped Small bunch each mint, parsley and coriander
• Thumb-sized chunk ginger, chopped
• 1 onion, peeled and chopped
• 5 tbsp olive oil