Outer Isles Gardening Celeriac Soup

Ingredients

• 25g butter
• 400g celeriac, peeled and chopped
• 125g potatoes, peeled and chopped
• 1 garlic clove, crushed
• 1 medium onion, chopped
• 570ml vegetable or light chicken stock
• 1 tbsp lemon juice
• 1 tbsp chopped parsley