Cream of Nettle Soup

2lb/900g young nettles
2 tbsp/25g/l oz butter
1 small onion, chopped
? cup/25g/l oz flour
3 ? cups/900ml/30fl oz milk
Salt and freshly ground black pepper
2 egg yolks
1 tbsp/15ml single cream and croutons to serve
serves 6
Pick the young nettle leaves before the plants flower. Discard the stalks, wash the leaves and press them into a pan with only the water that is clinging to them. Cover the pan and cook until soft (5-8 minutes). Puree in a blender.
Heat the butter in a pan and cook the onion until soft. Stir in the flour. Stir in a little milk and cook until thick. Stir in enough of the remaining milk to make a very thin sauce. Add the milk and the sauce to the nettles. Season well.
Beat the egg yolks with the cream. Stir in a little of the soup, then return to the pan. Heat through and check seasoning.
To serve, add a swirl of cream and some croutons to each individual bowl.