Spanish Mackerel a la Perigord

Pare the fillets removed from the mackerel into half heart-shapes; lay them in a buttered sautoir, decorating the thickest part of each fillet with a rose-shaped ornament of truffles dipped in egg-whites. Baste over with melted butter, lemon juice, white wine, and salt; cover with a buttered paper, and let cook in a slow oven. Dress the fillets, reduce their liquid, adding veloute sauce (No. 415) and slices of truffles fried in butter. Cover the truffles with a third part of this sauce, and glaze the fillets with fish glaze (No. 399) combined with lobster coral butter (No. 580). Serve the remainder of the sauce separately.