Roux, it’s a funny little word and an even funnier ingredient or mixture or whatever you want to call it. It’s one of the most important things when you are making soups or sauces. If you have cooked anything like that before (homemade gravy for instance) you have likely made this without even realizing it as most recipes don’t actually say “Hey go make a roux!” they just tell you do it. I think understanding what a roux is will allow you to full harness its power and up your sauce and soup game.
What Even is a Roux?
A Roux (pronounced roo like Scooby would say Scooby-roobie roo) is a mixture of flour and some fat that is often used to thicken sauces, soups or any other liquid that needs thickening. The word itself is French in origin but actually only means what it is, a mixture of fat and flour (as opposed to Al Dente that means ‘to the tooth’). Roux’s come in all sorts of colors and can be relatively mild in flavor or add a whole lot. The flavor can come from your personal choice of fat, or if you decide to cook the roux develop the flavor from the flour. Many dishes that utilize the roux are French in origin (but hey the French really did develop most contemporary cooking methods in general). These dishes mostly use lighter roux while cajun dishes use darker roux to get more flavor.
How Does it Work?
I love the science behind roux’s it’s really interesting as we can get brush the surface on the power of flour and why it’s such a useful staple in our diets. First off, flour contains a lot of starch in it. The thing is the starches are all jumbled and bundled up like a rubber band ball. Well, when you apply a liquid and heat, you cause the starch balls to burst open and spread all about the place. This is kind of akin to the peanuts can gag where you open it and the ‘snakes’ shoot all over the place.
If that explains the flour then why do we need the fat? Well when you make a roux you need need to mix it in evenly. If you just dumped the flour into the soup/sauce you would get balls of flour that won’t mix in completely. The fat ‘greases’ the flour just like you’d grease a pan. This allows the flour to not clump together and mix in smoothly with your other ingredients. Also the fat can be a great source of flavor if you use butter or something like renderings from bacon, turkey, ham etc.
There is several different types of roux to create. Each one has a bit of a trade off so you need to consider what your needs for the recipe are. Generally roux starts at a light or a blonde roux and then moves on to brown and dark roux the more you cook it. Lighter roux are less flavorful but thicken much better while darker roux offer more flavor but less thickening power. In most cases your roux is defined by how long you cook it but if you start with a very light oil like vegetable or canola you get a blonde roux.
Let’s Make a Roux
To make a roux you start with equal parts fat and flour. As a rule of thumb, if your making a creamy soup usually two tablespoons of flour to two tablespoons of fat will thicken up 2-3 cups of liquid. If your fat is solid then you will want to melt it at a very low temperature. After that you will add your roux and mix in the flour. You’ll create a nice paste like mixture.
If you are looking for a light roux you just bubble at medium heat it for a minute or two to help get the floury taste out and then you are ready to add whatever liquid concoction that you are stirring up into it!
If you are cooking a darker roux, tread carefully because it is way to easy to go from toasty, tasty goodness to burnt and ruined. You’ll want to keep that medium heat and stir and move around the roux constantly. It will bubble and slowly brown. If you stop while it’s at a caramel color you have a medium roux. If you keep going until it’s a great chocolate color, but not black, it’s a dark roux.
Creating a dark roux essentially is ‘toasting’ the flour so that you get a nice nuttiness that blends well with savory soups. Gumbo almost always starts with a brown roux as the key thickening agent here.
A Few Other Notes
You may know about a few other common thickening agents in cooking. You have gluten and pectin that are more often used for desserts as they create more of a gel like texture that you want. Eggs when tempered properly (we’ll talk about that another day!) can work as a very subtle and smooth mild sort of thickener.
There are other starches as well but by far the biggest competitor to a flour roux is the cornstarch slurry. I’ve seen some places that call cornstarch slurry (a mixture of water and cornstarch that is to be added to a hot mixture) as the better alternative to a roux. Heck no! Now there are some benefits to cornstarch slurry, it can be a little smoother and it doesn’t taste like anything on it’s own. With that said, I still don’t prefer it. To counter the second point, roux doesn’t have to taste like flour. If you ensure that you cook the roux a bit both before and after you add your liquid it will greatly reduces the floury taste. Secondly, my biggest issue with a cornstarch slurry is that can break. If you over cook a mixture with a corn starch slurry it can potentially separate and ruin your whole dish. It’s much too unstable for me and whenever I can I go for the roux.
One last tip: You can totally make up roux ahead and freeze it. Then just skip the roux step in any recipe and once your mixture is hot, add in the roux and it will beautifully melt and thicken your soup and/or sauce!
Thanks for reading, if you thought this post was useful pass it along! 🙂