A good roux can lay the foundation for a great sauce. This thickening base, if made properly, can act as the perfect addition to all manner of sauces, soups and gravies, and the basic mixture is incredibly easy to make. Here is a quick and easy recipe.
Melt clarified butter
A roux can be made with virtually any type of fat. Some cooks choose to make an oil-based roux, while other recipes include bacon or chicken fat. You can also use vegetable oil.
The traditional recipe uses clarified butter, though you can also use unclarified butter if you choose. If you don't have clarified butter, find out how to make it here.
To make this roux, your first step should be to melt two to three tablespoons of clarified butter into a pan.
Once the butter melts and starts to turn frothy, you can begin stirring in plain flour. Since the butter will need an equal amount of flour to be fully absorbed, you'll need to ensure that they are both added in equal measure.
Stir the mixture continuously with a wooden spoon or whisk until it gains a thick texture similar to wet concrete. Remember that you may need to adjust measurements slightly until you get it right.
Keep stirring the mixture over a medium heat for several minutes until it begins turning brown. However long you allow it to cook is up to you - the browner the mixture becomes, the more flavor it will have.
That said, be sure not to let it go darker than a mahogany color, as the mixture may burn. Once you've cooked the roux to your liking, place it in a container and allow it to cool.
To thicken a sauce with your newly made roux, let it cool to avoid spattering, then simply stir it into the mixture in accordance with the recipe.