A roux is a mixture of fat and flour that is used for thickening sauces. The technique involved in making a roux is vital to French cooking, as three of the “mother sauces” of French cuisine — béchamel sauce, velouté sauce and espagnole sauce — all have the roux at their roots. Fortunately, roux is not difficult to make and it will add a great tool to your culinary toolbox!
About the ingredients
The two main ingredients in a roux are fat and flour. The fat is typically butter though it is possible to use rendered animal fat (such as bacon fat or even olive oil) for roux with a unique flavor. Butter is a nice building block for almost every dish, especially when it comes to French cooking, and you can’t go wrong when you use it.
I recommend using a good quality unsalted butter. Salt will be added to any sauce that you thicken with a roux and it is best to have a neutral base to start out with.
When it comes to flour, pantry-staple all purpose flour is a good choice. The flour is added to the fat all at once and cooked until the flour-y flavor of the wheat is gone, then you can add the liquid you want to thicken and cook until your sauce comes to the thick, smooth consistency that you are looking for.
The ratio of fat to flour used in a roux is always 1:1, however the exact amount of fat and flour that you use will vary from recipe to recipe. For instance, a thick sausage gravy that is destined to be served with buttery biscuits might need more roux to produce a hearty enough sauce to stand up to oversized biscuits. By contrast, a béchamel will become the base of a cheesy pasta sauce may need less roux, since you will be adding cheese to thicken the sauce later in the cooking process. In general, I find that 2 tablespoons of butter and 2 tablespoons of flour thicken 1 1/2 cups of liquid to a nice not-too-thick consistency and I use that as a starting point for many recipes.
Regardless of how much roux you are making, the process is always the same and following these steps will ensure your roux turns out just right.
How to make a roux
- 1 part butter (or another fat)
- 1 part all-purpose flour
Melt the butter in a saucepan over medium heat.
When the butter is melted and bubbling, add the flour all at once.
Whisk or stir constantly until the flour is completely incorporated and the mixture begins to thicken. Mixture may look slightly lumpy at first, but it will smooth out quickly.
Add in the liquid you want to thicken. For instance, you can add milk to make a creamy béchamel sauce or pot roast drippings to make a hearty gravy. Once the liquid is added, continue stirring until the mixture simmers and thickens.