25g butter, 1 red onion finely chopped, 400g potatoes, diced, 1 litre chicken stock, sea salt and ground black pepper (for seasoning) & fresh parsley.
Method:
Melt 25g butter in a large heavy pan and add 1 red onion, finely chopped, turning them in the butter until well coated. Cover and leave to sweat over a very low heat.
Add 400g potatoes, diced, to the pan, and mix well with the butter and onions. Season with sea salt and ground black pepper, cover and cook over a gentle heat for about 10 minutes, without browning. Add 1 litre chicken stock, bring to the boil and simmer for 20 minutes, or until the vegetables are tender.
Remove from the heat and allow to cool slightly. Purée the soup in batches in a food processor or blender.
Reheat over a low heat and adjust the seasoning. If the soup seems too thick, add a little milk to achieve the required consistency. Serve hot, sprinkled with chopped fresh parsley.