The magic in cajun cooking.
I know of three ways of making a roux.
The recipe is the same for all: equal parts flour and oil.
Method one is to use a low or medium heat on the stove and warm the oil. When it is warm, but not too hot, add the flour and with a wooden spoon, stir. And stir and stir. For an hour or an hour and a half or so as the mixture darkens. before it reaches the color of peanut butter, the stirring can be kind of hap-hazard, just enough to keep things from sticking—which is pretty much the same throughout the whole process, except that the darker the roux gets, the faster the stirring to keep it from sticking and burning.
Method two, I have only read about and uses very high heat and results—theoretically—in black roux in 12 minutes. This method has been described as working with Cajun Napalm and is beyond my risk-tolerance level, but check out this article for how it might be able to be done.
Method three is now my favorite (unless I want to be left alone for the 90 minutes or so). Some call it cheating, but a black roux is a black roux, and this method is less likely to burn than the other two. In a heat-proof and microwavable dish, whip with a wire whisk equal parts oil and flour and heat on full power in three – five minute increments until it gets to the peanut butter color stage. After each five minutes, carefully whisk the mixture again to even things out. After that, do it in 30 second intervals until it is chocolate, then in 10 second increments. If it starts to get a smoky smell: stop or you will burn it. This whole process takes less than 15 minutes.
Whichever method you use, try to let it cool down a bit and pour off the oil that forms on the top before using it in a gumbo or etoufee or soups or, well, whatever your imagination can conjure.
The picture is from kitchen.com