Roux
Roux () is flour and fat cooked together and used to thicken sauces. Roux is typically made from equal parts of flour and fat by weight. The flour is added to the melted fat or oil on the stove top, blended until smooth, and cooked to the desired level of brownness. Butter, vegetable oils, bacon drippings or lard are commonly used fats. Roux is used as a thickening agent for gravy, sauces, soups and stews. It provides the base for a dish, and other ingredients are added after the roux is complete.
Service à la russe
In Britain and the United States, fish is a distinct course; relevés are large, solid joints of meat or whole fowl, generally baked, braised, or boiled but not roasted; entrées are elaborate "made dishes" of, typically, fillets of beef or other butcher's meat (and sometimes fowl, but—apart from days of religious observance—not fish), served in fine sauces. Roasts are solid joints of meat (and sometimes fowl) other than feathered game, usually spit-roasted but often baked. Game is feathered not furred, spit-roasted whole and served rather simply. (Rorer's "roast" here refers to a roasted entrée, but this terminology is not typical of the period. In her time, the "roast" followed the punch, and it was always game, if available.)