Roux is a French word referring to a dough, made with butter and flour in equal parts, which serves as a base for different sauces. Depending on the degree of toasting of the flour, the roux can be white or blonde. Diluted with milk, it is used for bechamel, while if diluted with chicken or fish broth it produces a chicken or fish soup; when darker, it is possible to obtain the red roux for the Spanish sauce.