If you’ve ever made traditional macaroni and cheese, you’ve made a roux. You know that mixture of flour and butter that gets added in with the milk? Bingo. Ever had chowder? What do you think thickens it? That’s right! A roux. The majority of soups and sauces are thickened with a roux. This article is for everybody who enjoys a bowl of gumbo, or a nice creamy alfredo as the cooler weather approaches.
So what is a roux? By definition a roux is a mixture of equal parts starch and fat. The starch and fat are measured by weight, not volume. For example, instead of measuring one cup of butter to one cup of flour, one would use a kitchen scale to measure 8 ounces of flour to 8 ounces of butter.
A roux is traditionally made with clarified butter. That is, butter that has been melted, and skimmed to that the milk solids and water have been removed from the butterfat. Clarifying the butter is not essential for everyday purposes, and you can make a roux from unclarified butter, bacon fat, or any combination of oil and flour.
To make a roux, you are going to add the oil first to a pan. After the oil is melted and warm, add the flour. The mixture should be the consistency of wet sand. Continue cooking on medium to low heat until, at a minimum, the flour taste is removed from the mixture. After that, the cooking time will vary based on the color roux you desire to make. A dark roux will take longer to make, up to 45 minutes. A white roux takes the shortest amount of time, as you only need to cook it until the floury taste is removed.
There are three basic kinds of roux. A white roux is used in sauces that are milk- and cream-based. A blonde roux (cooked a bit longer) is used in lighter stocks, such as chicken or turkey stock. A brown roux is used to thicken brown stocks and sauces. It should be cooked over low heat, so the butter and flour do not burn. It should smell nutty, not charred.
After the roux is made, the next step is to add it to your stock or sauce. The amount you add depends on what you’re making. For a heavy gravy, use 6 ounces or roux per quart. For a medium body sauce, use 4 ounces per quart. A white roux has more thickening power than a dark roux. To thicken, you should add a warm or cold (never hot) roux to your stock. A hot roux may break when it hits a sauce, thus losing its thickening power. Whisk the mixture vigorously, and simmer for around 20 minutes. The simmering will help further remove the taste of raw flour from your stock or sauce.
A roux does not need salt or any other seasoning. You will season the dish upon completion. Use unsalted butter if you choose butter as your form of fat. You want to control the amount of salt that goes into the dish. Choosing pre-salted products could result in a dish that is too salty. If you use rendered bacon fat, be aware that your thickening agent contains salt, and you may not need to add any salt at all to your finished product.
These days, cornstarch is also a common thickener. What is the advantage of using a roux instead? A cornstarch slurry will deaden the flavors of your dish. Think about it— You’re adding water, but no seasonings. Further, a dish thickened with a roux will hold up better over time.
How thick do you want your sauce or soup? As a general guide, thicken it until it easily coats the back of a spoon. This is called a la nappe. This consistence will coat a dish perfectly, and result in a sauce that is neither to think nor too runny.
This fall, when you make a pot of soup to get you through the week, don’t just throw flour into the pot. Don’t use flavor-killing cornstarch. Take the time to make a roux and thicken the dish properly. Your taste buds will thank you.