To fillet the mackerel, place the fish on the table with the head to your right and its back towards you; then run the knife in, just below the gills; turn the edge of the blade under; press with the fingers full on the upper end of the fillet, and bearing with the blade of the knife gently down to the tail, the first fillet will thus be removed; repeat this action on the side of the backbone, and then, dividing the fillets into halves crosswise, trim off the black inside skin and bones; cut off the corners, and arrange the fillets in symmetrical order in a sauta-pan containing two ounces of dissolved butter; season with pepper and salt, lemon-juice, and chopped parsley; set them over the fire, or in the oven for twelve minutes, and when done through, drain and dish them up in circular form; place the roes (previously parboiled in water with a little vinegar and salt) in the centre; pour some maitre-d'hotel sauce, No. 32, over all, and serve.
Note.—Fillets of mackerel prepared as prescribed in the first part of the foregoing directions may also be served with any of the following sauces, viz.:—ravigotte, Dutch, brown butter, piquante, matelotte, or Genoese.