Buy either a thick slice as for boiling, or thinner ones as for frying. In the latter case, pile them up with lumps of butter between the slices.
Put several lumps of butter in the bottom of a tin pan. Lay in the fish, sprinkled with pepper and salt, and set it in the oven which should not be very hot. In about fifteen minutes pour over it one pint boiling water (or enough for gravy), flour it, and leave it till it is tender when pierced by a fork. Then put the fish in a platter, with a little butter, and keep it hot while you make the gravy. Set the pan on top of the stove, let the gravy boil, and thicken it by dredging in flour. Stir while it thickens, and then pour over the fish.
Buy a thick piece to boil. Boil like other fish (see "To Boil Fish"), but without a cloth, if you choose, as the texture of this fish is so firm as not to be in danger of breaking, if boiled slowly. Boil five or ten minutes to the pound, from the time it begins to boil.