340g/12oz skinless chicken breast, minced (ground)
1 large leek, thinly sliced
2 celery sticks, thinly sliced
1 large carrot, thinly sliced
1 small onion, chopped
2 medium (US large) egg whites, beaten, and their shells, crushed
1.7 litres/3 pints/7½ cups hot chicken stock
a dash of sherry or Madeira
salt and ground black pepper
1 Put the chicken and vegetables in a large pan and mix in the beaten egg whites and egg shells.
2 Gradually whisk in the hot stock, then bring to the boil, still whisking. As soon as it starts to boil, stop whisking, reduce the heat and simmer very gently for 1 hour.
3 Make a hole in the surface crust and ladle the clear stock underneath out into a muslin (cheesecloth)-lined sieve placed over a large bowl.
4 Leave the stock to drain through slowly. Pour into a clean pan and reheat gently. Season to taste and flavour with a little sherry or Madeira.