Boil one pound and a half of any white fish, cod preferably, in salted water until cooked. Then take out the fish and carefully remove skin and bones.
Boil about half a dozen medium-sized potatoes in some of the fish water till well cooked.
Boil a plateful of onions cut in slices in milk, adding a piece of bacon (to be removed before serving).
Mix together the fish, potatoes and onions, leave a certain amount of the two stocks (two-thirds of the milk to one-third of the fish-potato stock), add a piece of butter the size of a small egg, pepper and salt, and bring gently to the boil. Let it be reduced to the consistency you like. It should, however, be served rather thick.