Step 1

Melt the lard or some other fat (like peanut oil, vegetable oil, or bacon grease) over high heat in a large cast iron skillet.

Step 2

Gradually whisk in the flour until it is well mixed.  Whisk constantly until the mixture begins to bubble, then keep stirring.   After 5 minutes, turn down the heat to medium high.

Step 3

Continue whisking constantly, making sure to stir at the edges of the pan as well.  After a few minutes, the flour mixture will start to change color.  Once it turns a light caramel color, turn the heat down to medium.

Step 4

If you like, exchange your whisk for a wooden spoon, but keep stirring constantly.  The flour will continue to change color over a period of time.  In the next color stage, it will be a light peanut butter color.  You might want to keep a jar of peanut butter out to compare.

Step 5

To have a Creole type gumbo, you will want the roux to be the color of a copper penny.  This will require about 20-30 more minutes of constant stirring.  Be patient--it's worth it.  If you want, you can keep a penny close by to compare.  The smell of the flour browning should give off a nutty aroma.  If you smell it burning, lower the heat or move the cast iron skillet off the burner for a while.  If there are black flecks in the roux, it is burnt and you'll have to start over, as a burnt roux will taste bitter.  Your goal is to have it a smooth and silky consistency, not lumpy.

Step 6

If your goal is to have Cajun type gumbo, you will want your roux to be a darker reddish brown color.  In order to achieve this, turn the heat down to low.  This will allow you to control the color of without burning it.  Keep stirring until you are almost at the desired color.

Step 7

Remember, the roux darkens and continues to cook when it's removed from the source of heat, especially if it's in a cast iron pan.  Because of this fact, it's a good idea to turn off the heat and remove it from the burner when it's one or two shades lighter than you want it to be.  Continue stirring until it cools, roughly 5 minutes.