A roux is a mixture of flour and fat, typically equal parts, used to thicken sauces in classical cooking. And it’s a recipe must-have if you want to achieve macaroni and cheese nirvana or the perfect Thanksgiving gravy.
Because raw flour is used, a roux needs to be cooked to remove the raw flour taste that can transfer to the sauce or soup being thickened.
The longer a roux is cooked, the darker it becomes, changing its flavor profile at the same time. Delicate blond roux are used for light chicken and fish sauces such as chicken or fish veloute. A darker blond roux is perfect for sharp cheddar macaroni and cheese or cheddar cheese soup. A dark roux will give stews a robust flavor, while a black, or Cajun, roux gives gumbo its distinctive color and depth of flavor.
A dark or black roux takes time and dedication, with a watchful eye and constant stirring. To save yourself time in front of the burner, toast your flour in a 350 degree F oven until it turns the desired shade, then cook with melted fat as described in our how-to below.
About one tablespoon of roux will thicken one cup of liquid to the consistency of a thick gravy. Adjust the amount of roux or liquid until the desired consistency is reached in your sauce or soup.
Step 1: Measure
Measure equal amounts of fat and flour. Fat can be in the form of whole butter, clarified butter or oil of your choice.
Step 2: Cook
Heat the fat and flour mixture over medium-low heat for at least one minute to prevent the raw flour flavor from transferring to your sauce.
Step 3: Thicken
Whisk in desired liquid, according to your recipe, to thicken your sauce or soup. Bring to boiling and then reduce to a simmer to allow the starch molecules to absorb the maximum amount of moisture and expand.
You can also create a cold roux, called a “beurre manié,” by mixing equal parts of fat and flour by hand to create a dough. The dough can then be added to hot liquid to thicken.