Roux, is a French word meaning "reddish brown," and is pronounced "roo." The Roux is the heart of many Cajun and Creole recipes and its worth the time to learn how to make it properly. It's directions are very simple. Just remember one thing: if you burn the Roux, THROW IT AWAY, clean the pan, and start over again. A burned roux will ruin the taste of the dish. 

There are three categories of Roux: 

...a light Roux (or "blond" Roux) 
...a medium Roux (golden brown) 
...a dark Roux (a deep brown color) 

Stovetop Directions: 

In a frying pan or cast iron skillet put in 1 cup of cooking oil (or for a richer Roux use some fresh bacon grease) and heat on medium high. Slowly stir in 1 cup of flour until the mixture is smooth and creamy and continue stirring for 5 minutes. Reduce the heat to medium and continue cooking and stirring to keep the Roux from sticking. Cook Roux until the desired color is obtained. If you have any pan drippings from a roast or other meat, add it in and continue cooking. In my Roux I also like to add onion and garlic. You are only limited by your own imagination. 

Always make a little more Roux than the recipe calls for. You might want to add extra Roux to the dish if it's not thickening the way you wish. 

Microwave Directions: 

Mix 1 cup of cooking oil and 1 cup of flour thoroughly in a microwave bowl. Cook on HIGH (Full Power) for 6 minutes. STIR. Cook another 3 minutes. STIR. Cook at 1 minutes intervals, stirring in between. When color is about right, add onion, garlic, drippings and cook for 1 more minute.