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.
Rouen duck
The plumage coloring of both the Rouen drake and the Rouen duck are nearly identical to that of the Mallard drake and Mallard duck. The Mallard color pattern is referred to as gray. Males have green heads, white collars, black tail coverts and dark, ashy brown tail feathers, a gray body, and a deep claret breast. The female Rouen hens are a consistent shade of mahogany brown, with a brown crown and tan eye-stripes extending from bill to the back of the eyes. Another feature of the female color pattern is the distinct, detailed penciling found on feathers of the head, neck, body, body, most of the wing and tail. Rouen females can be much darker brown than Mallard females. Both sexes also have blue speculum feathers. However, Rouen speculum feathers are brighter in color and larger in size than that of the Mallard. Adult Rouen ducks are typically significantly larger than Mallard ducks. The Rouen duckling is identical to the Mallard duckling in terms of plumage coloring. In North America, two distinct types are bred: the common, or production-bred, variety that is larger than a Mallard but has a typical duck conformation, and the much larger and squarer standard-bred variety. The production variety normally weighs 6–8 lbs (2.7–3.6 kg) while the standard-bred weighs 9–12 lb (4.1–5.4 kg).