Thai coconut prawn curry

Ingredients

• 1 onion, quartered
• 3 garlic cloves
• 3-5 long green chillies (depending on how hot you like it)
• 2 lemongrass stalks, tough outer leaves removed and insides chopped
• Zest of 2 limes
• Handful of coriander stalks
• 2.5cm piece of fresh ginger, grated
• 2 tsp shrimp paste (we like Thai Taste, from supermarkets)
• 200ml coconut milk
• 5 kaffir lime leaves (from larger Sainsbury’s)
• 500g raw, peeled sustainable prawns
• Fish sauce
• 2 tsp soft brown sugar or palm sugar
• Juice of 2 limes
• Fresh coriander sprigs to serve