Put the meat, bones, giblets (if you are using them), the vegetables. peeled and cut up coarsely and a good pinch of salt into a large pan and cover with nearly 3 litres (5 pints) of cold water. Add the beaten egg white last of all.

Bring slowly to the boil, whisking energetically from time to time, until the white of the egg and impurities form a frothy lid on the top. Allow to simmer, almost imperceptibly for 2 1/2 hours or even longer, although 5 hours will exhaust all the flavours and nutrients.

Strain the broth into a bowl through a clean tea towel, rinsed out in cold water and placed over a colander. Rinse the cloth and repeat the performance, to remove the last traces of the egg-white filter. Taste for seasoning.

At this stage, if the potage is to be served hot, return it to the carefully rinsed pan. If it is to be served cold, put it, cooled, into the refrigerator. It must be either piping hot or properly chilled.

The sherry, like all fortified wines - others include port, Madeira, Marsala - has a short-lived flavour and should be added almost at the last moment.