Boiled Mackerel (Fresh)

Product Description
This recipe (and the variation for salted mackerel) is taken directly from the book, "Common Sense in the Household: A Manual of Practical Housewifery" by Marion Harland. Published in Toronto by Rose Publishing Company, circa 1900.
Boiled Mackerel. (Fresh.)
Clean the mackerel and wipe carefully with a dry, clean cloth; wash them lightly with another cloth dipped in vinegar; wrap each in a course linen cloth (floured) based closely to the shape of the fish. Put them into a pot with enough salted water to cover them, and boil them gently for half an hour. Drain them well. Take a teacupful of the water in which they were boiled, and put into a saucepan with a tablespoonful of walnut catsup, some anchovy paste or sauce, and the juice of half a lemon. Let this boil up well and add a lump of butter the size of an egg, with a tablespoonful of browned flour wet in cold water. Boil up again and serve in the sauce-boat. This makes a brown sauce. You can substitute egg-sauce if you like. Garnish with parsley and nasturtium blossoms.
Boiled Mackerel. (Salt.)
Soak over night in lukewarm water. Change this early in the morning for very cold, and let the fish lie in this until time to cook. Then proceed as with fresh mackerel.