A roux (pronounced ROO) is a French term for a mixture that is comprised of flour and fat, usually butter. A roux can be cooked to different stages depending on the color and flavor that is desired. A roux is typically used to thicken gravies, sauces, soups, and gumbo.
To make a roux, a 1:1 ratio of flour to fat is always used. First, heat the butter or oil over medium heat then evenly sprinkle the flour on top. Continually whisk the roux for 5-7 minutes, this will allow the raw taste of flour to cook out. At this point it is considered to be a “blonde roux” which is optimal for thickening purposes. If cooked past 7 minutes the roux will darken and develop a more nutty flavor but it will also lessen its thickening abilities. A dark roux is best for Cajun dishes such as Étouffée or gumbo.