This is honestly a post I should’ve written quite a while ago, but better late then never.
Today I want to talk about Roux (pronounced roo, think kangaroux). Roux might be one of the most influential fundamental culinary devices, yet civilians seem to have little to no knowledge of it.
Roux’s primary use is to thicken liquids, usually sauces, though its found in soups, stews, casseroles, chilis, pot pies, you get the idea. Its everywhere. It’s also the culprit behind a lot of seemingly gluten free items not being gluten free. If you have a gluten issue jump to the section at the bottom regarding cornstarch slurry.
Roux, like much of classic French cooking, is a complex handling of simple ingredients. To create a basic roux you simply must measure out, by weight, equal parts butter and flour. Melt the butter then whisk in the flour little by little until you start to get a play-doh like mass that’s off white, almost manila, in color. As it exists in this form, uncooked and pale it is a White Roux, good to use in a pinch when you’re in hurry, especially for something you intend to cook further, like a soup or stew, as it imparts an unpleasant raw flour taste to whatever its stirred into. This must be cooked out over time.
Know comes the complicated bit. Roux’s special nature is only brought out by cooking it, carefully. Roux requires quite a bit of heat and time to alter it, but it’s also quite prone to burning. This means you must monitor your heat and constantly stir it, and stir it well. The best tools for handling roux are a sauce pan (that is a pan with tall sides and rounded “corners” where the walls meet the bottom) and a very stiff wire whisk. Roux goes through many changes and at any given point on its journey it is uniquely useful, though today I’ll cover a total of five stages (including the previously mentioned White Roux) all the way up the famous Cajun Brick Roux.
Starting with your newly formed white roux, cook over low heat (you can go up to medium heat if you keep it moving properly, though its not recommended for beginners or those who lack the time to constantly watch it) for about two minutes just until it gains a slight bit of color and begins to smooth out. This is a Blonde Roux. Its good for any application, and its much less raw tasting them the White Roux, meaning it doesnt need to be cooked out after being incorporated into the sauce, soup or what have you.
Now if you keep cooking from here you’ll enter the territory of the Brown Rouxs. After another 2-3 minutes you’ll have a Lite Brown Roux that will start to have a nutty aroma, almost like buttered popcorn. This aroma will translate into flavor when you incorporate it into something. For this reason Brown (and eventually Brick) Rouxs are not universally applicable, like the White and Blonde Rouxs. You need to take into account that nutty flavor, which will be quite mild with a Lite Brown Roux but as it gets darker and darker the flavor will get more intense.
Another side effect of the continued cooking is that the thickening power of the roux goes down meaning that you’ll need more of a darker roux to do the same job that a liter roux does, regarding changes in viscosity. Keep this in mind, and its always best to create more roux then you feel you’ll need, just in case.
Now as you continue to cook your roux it’ll begin to get much much darker in color, and the aroma will go from buttered popcorn to almost burnt popcorn, becoming much more intense as it does. This is a the fabled Brick Roux featured strongly in Cajun and Creole cooking. It’s very potent JuJu, flavor-wise, and will drastically change the taste of a dish when incorporated.
Once your roux is cooked to its desired level you must now consider how it will be incorporated. The main rule regarding roux incorporation is The Rule of Opposites. That is, your roux and your liquid must be opposite in temperature when being combined. If you just created your roux and it is hot in the pan, you must add a cold liquid to it. If you have a boiling liquid you wish to add a roux to, to thicken it, the roux must be “cold” (read: room temp) Following this rule will ensure that you dont end up with clumps of incorporated roux in your final dish (which are fucking disgusting to bite into).
That being said, I almost always use a cold roux into a hot liquid. I find it much easier to handle, and it has the added benefit that its very easy to adjust, since you can simply add the roux slowly, and add as much as you need to achieve a desired thickness.
When storing roux never refrigerate it. It will solidify into an incredibly hard brick and become unusable. Store it in a well sealed air tight container on the counter for up to a week.
Now there is another kind of Roux, made with oil, I call it a quick roux. Its very useful for soups, as its as raw as a White Roux so requires a good amount of post incorporation cooking to remove the floury taste. Its quite simple to make, just add an amount of flour into a bowl or container and mix in enough oil until you get a very thick liquid. You want your Quick Roux to be much looser then a normal butter roux, I find it doesn’t incorporate as well as normal rouxs, and making it so thin that its easily pourable helps overcome this issue.
When incorporating a Quick Roux you’ll want the liquid to be below a simmer in temperature and you’ll want to stir vigorously as you pour it in. The biggest issue with Quick Rouxs is that they tend to set before you get a chance to fully disperse them into the liquid, resulting in little blisters of unpleasantness in your soup.
Finally, Id like to talk about cornstarch slurries. While wholly unrelated to Roux, it does do the same job, thickening liquids, and it does so in a gluten free manner. Simply combine equal parts (by volume this time) cornstarch and water and whisk to combine. (I actually prefer to place the ingredients in a small air tight container and shake the hell out of them) Slurry thickens much more efficiently then roux, but provides no flavor, and in large quantities actually has an anti-flavor effect, dulling the taste of whatever its used on. It also produces a glossy sheen when incorporated. This makes it good for things like desserts, but less then desirable for things like sauces of stews. You can offset this sheen by adding some high fat dairy (if applicable) to the recipe.
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