Moroccan lamb with dates

Ingredients

• 1 tbsp olive oil
• 1 onion, finely chopped
• 500g diced boneless lean lamb, preferably from the leg
• 300g sweet potatoes, cut into small chunks
• 2 tsp ground coriander
• 2 tsp ground cinnamon
• 1 tbsp tomato purée
• 50g pitted dates
• 2 tbsp coriander, roughly chopped
• 25g roughly chopped pine nuts, as garnish (optional)