Celeriac Soup - River Cottage

Ingredients

• 50g Butter
• 1 Celeriac, peeled and cubed
• 1 Potato, peeled and cubed
• 1 Leek, trimmed, washed and roughly sliced
• 1 Onion, peeled and roughly chopped
• 1 Garlic clove, sliced
• 1 litre vegetable stock (or chicken if preferred)
• Parsley & walnut pesto to serve