Watercress Soup

recipe-01 1 onion, chopped
25g butter
250g potatoes, diced
600ml chicken stock
2 bags or bunches of watercress, chopped
(use any stems left from other recipes too)
50ml cream
a little milk if needed

In a large pan, sweat the onion in the butter until soft but not browned. Add the potato and stock, and cook until the potatoes are soft (approx 15-20 minutes). when potatoes are almost cooked, add the watercress  (try to allow not longer than 5 minutes cooking time for the watercress). Liquidise, add cream . Use a little extra  milk if the soup seems to thick. Season with salt and black pepper and serve hot.