Ingredients

• 1 tbsp groundnut oil
• 1 onion
• peeled and finely chopped
• 1 garlic clove
• crushed
• 1.25cm/½in piece fresh ginger
• peeled
• 675g/1½lb sweet potatoes
• peeled and diced
• 1 tbsp chopped lemongrass
• 570ml/1 pint vegetable stock
• 1 x 400ml tin coconut milk
• salt and freshly ground black pepper
• 2 limes
• zest and juice

Directions

• Heat the oil in a large saucepan and gently fry the onion
• garlic and ginger for about 5 minutes until tender. Add the sweet potatoes and lemongrass and cook for a further 3 minutes.
• Add the stock and bring to the boil. Reduce the heat and simmer for 20 minutes until the vegetables are tender.
• Cool the soup slightly
• then liquidise with the coconut milk and process until smooth. Season with salt and pepper. Heat through without allowing the soup to boil
• and add the lime juice. Ladle the soup into bowls and garnish with the lime zest.