A Cajun roux starts out in a large cast iron pot over medium heat. With no distractions and approximately one hour of time at your disposal, begin by adding the flour and oil.With a long-handled wooden spoon, begin to stir. Constant stirring and moving the flour around the bottom of the pot is the key to browning the flour evenly to prevent burning. This early stage will go slowly as you begin to see the white flour take on a beige and then a tan color.Continue stirring slowly and evenly, scraping the bottom and the circular crevices of the pot to move the flour around in the hot oil.At about the half-hour mark, you will begin to see a brown color developing and smell the first hints of toasted flour. This is where the stirring becomes even more crucial.At this point, you begin to enter the quickly developing phase where the least bit of inattention could result in burnt flecks of flour appearing – a sure sign you’ve ruined the roux. Watch your heat and lower it if the roux is cooking too fast.Constant stirring to keep the flour from staying in one place too long prevents burning. You will begin to smell an even nuttier aroma as you see the color turn darker mahogany. Most stop here, but you will keep going until you achieve a deeper, darker chocolatey consistency and color.Forget time at this point since you are now cooking by instinct, sight and smell. The utmost attention is needed to your stirring, and when you see that Hershey chocolate darkness, you will know you have arrived.Turn off the heat, but continue stirring until it begins to cool down and quits cooking.Spoon the roux into a bowl and let cool.