You Can't Judge a Roux by Its Color (Patreon)

Following up on Cookbook Club experiment: A More Foolproof Way to Make Dark Roux.

Last week, I wrote about my plans to test a few potentially more foolproof ways of making dark roux, inspired by coming across an excellent tutorial by Louisiana chef Adriánna Guillory-Bellow on how to properly make a slow-cooked dark roux, the cooked flour and oil mixture that gives gumbo its distinct color and deep flavor.

Well I got around to doing that testing and found something really interesting.

I made four batches of dark roux:

Clockwise, from the upper left:

By toasting raw flour in the oven until it hit a deep cinnamon color, then stirring it into oil.

Flour and oil on the stovetop with constant stirring.

By combining flour and oil, spreading it on a sheet tray, and toasting it in the oven.

Flour and oil in the microwave, heating and stirring at 30-second intervals.

All four methods produced a roux that looked nice, evenly dark, and gumbo-worthy. But tasting them revealed something different.

Batches one and three—the ones I toasted in the oven—had a rich, nutty depth with layers of toasty flavor. Batches two and four, on the other hand, looked good and smelled good but had a distinctly bitter, burnt aftertaste.

What gives?

The problem is that color is not actually a great indicator of how dark your roux truly is.

Stovetop cooking is intensely directional. All the heat is coming from the bottom. So when you're making roux in a pan, the flour right against the bottom is getting heated faster than the flour above it. Low heat and stirring keeps things moving so that ideally all of those little particles get roughly the same treatment and brown to the same degree. That's the work Chef Guillory-Bellow demonstrates.

The problem is that its virtually impossible to stir the mixture fast enough to truly evenly cook it. Instead, once your roux looks nice and dark, in reality you have a mixture of some flour particles that have gone too far, and some that haven’t cooked far enough. The color may look right, but the flavor won’t follow through.

An oven, on the other hand, heats from all around and thus cooks much more evenly than the stovetop. The result is flour particles that brown at the same rate, creating a roux that is deeper in flavor with none of the bitter notes of burnt flour.

It’s kind of like mixing paint. You can start with a green pigment, or you can mix yellow and blue to get something that looks like a similar green. Looking at the finished color the two swatches might look identical, but one of them is a pure green pigment while the other is a mixture of blue and yellow.

Roux isn't paint, obviously, but the analogy is useful; a mixture of lighter flour and very dark, burnt flour can give you a brown that looks convincing. Mixing them together doesn't undo the burning. You can wind up with the bitterness of burnt flour and still be missing the fuller toasted flavor you wanted.

A few of you were already ahead of me in the comments on last week's post. Jerri described toasting flour, making an oven roux, then finishing it on the stovetop to get the desired chocolate color. (I personally found that I got better results with no stovetop cooking whatsoever.) Jerri also keeps toasted flour in the freezer, which I may have to start doing.

Stu K. mentioned having good results with Alton Brown's oven roux, with occasional stirring, and Josh W. pointed to Tim Hayward's writing on the oven method. I’ve been convinced that the oven method is, in fact, superior.

For now, this is a dispatch from the middle of testing, rather than a finished method with a temperature and timer attached. My main takeaway is that two roux can look very similar and taste very different. Color is a useful guide, but it isn't the whole test.OK, back to making gumbo!