Pike or Carp Balls

Here a really interesting receipt
you can use any fresh water fish, this receipt was written for either Pike or Carp

1kg/2lb pike or carp
1 onion
150 - 300 ml/quarter to half a pint dry white wine
1 bay leaf
4 eggs
pinch of salt
pinch pepper
pinch grated nutmeg
150g/5 oz butter
100 g/4 oz flour
250 ml/scant half pint milk

Skin and bone the fish. Peel the onion. Place the fish trimmings in a pan with 300 ml (1/2 pint) water, the wine, onion and bay leaf. Bring to the boil and simmer for 15 minutes. Strain and season the fish stock. Cut the fish into pieces and purée in a liquidiser, or chop finely. Separate the yolks from the eggs whites and whisk the whites until firm. Mix in the purée fish, season with salt, pepper, and nutmeg and leave in refrigerator for 30 minutes. Make a thick sauce with the butter, flour and milk. Cool, then gradually add the egg yolks and fish purée. Shape the mixture into balls and cook in the fish stock for 15 minutes. Remove with a draining spoon and serve with spinach and buttered potatoes. - Serves 4