Barbecued leg of lamb with Thai green spices

INGREDIENTS

• 10 kaffir lime leaves, torn
• 2 thumb-sized pieces fresh ginger, peeled and roughly chopped
• 2 sticks lemon grass, trimmed and roughly chopped
• 4 cloves garlic, pressed
• 1 bunch fresh coriander, leaves picked
• 2 green chillies, roughly chopped
• 4 tablespoons olive oil
• juice of 2 limes
• 1 x 2-2.5kg quality leg of lamb, butterflied
• sea salt
• freshly ground black pepper
• 400 ml coconut milk
• 1 fresh red chilli, deseeded and chopped
• juice of optional 1 lime