Cut into small delicate slices, or into scollops of equal size, sufficient cold calf's head or veal for a dish. Next knead very smoothly together with a knife two ounces of butter, and a small dessertspoonful of flour; put these into a stewpan or well-tinned saucepan, and keep them stirred or shaken over a gentle fire until they have simmered for a minute or two, but do not let them take the slightest colour; then add to them in very small portions (letting the sauce boil up after each is poured in) half a pint of pale veal gravy, or of good shin-of-beef stock, and when the whole is very smoothly blended, and has boiled for a couple of minutes, mix together and stir to it a tablespoonful of common vinegar, a dessertspoonful of Chili vinegar, a little cayenne, a tablespoonful of good mushroom catsup, and a very small bit of sugar; and when the sauce again boils, strew a tablespoonful of minced parsley over the meat, lay it in, and let it stand by the fire until it is quite heated through, but do not allow it to boil: if kept just at the simmering point for ten or twelve minutes, it may be served perfectly hot without.
The addition of the mushroom catsup converts this into an English sauce, and renders it in colour, as well as in flavour, unlike the French one which bears the game name, and which is acidulated generally with lemon-juice instead of vinegar. Pickled mushrooms are sometimes added to the dish: the parsley when it is objected to may be omitted, and the yolks of two or three eggs mixed with a little cream may be stirred in, but not allowed to boil, just before the meat is served. When veal is used for this hash instead of calf's head, it should be cut into slices not much larger than a twenty-five cent piece, and freed entirely from fat, sinew, and the brown edges. When neither broth nor gravy is at hand, a morsel or two of lean ham, and a few of the trimmings or bones of the head or joint, may be boiled down to supply its place.
Sufficient cold calf's head, or meat, for a dish; butter, 2 ozs.; flour, 1 small dessertspoonful; gravy, or strong broth, 1/2 pint; vinegar, and mushroom catsup, of each 1 tablespoonful; Chili vinegar, 1 dessertspoonful; small bit of sugar; little cayenne, and salt if needed parsley, 1 tablespoonful (pickled mushrooms or not at pleasure).