Roux is a mixture of equal quantity of Flour And Butter (Fat) cooked to a desired consistency. There are 3 desired consistencies to achieve roux and used as thickening agent for following mother sauces
White roux is for bechamel
Blond roux is for veloute and
Brown roux is for Espagnole sauce or brown sauce.
HOW TO MAKE ROUX?
Making roux is easy and simple to learn. For all the three types – white, blond and brown the method is same.
Heat Butter or fat such as oil in a deep saucepan.
Add refined flour to the butter and stir in to form a rough paste. The ideal flour to use is cake or pastry flour as it contains excess starch content, although an all-purpose flour can be used.
Cook the paste over medium heat until the desired consistency is achieved.
Equal amounts of fat and flour cooked till raw flour taste goes off, while the color is still white. The appearance should be foamy or bubbly.
Equal amounts of fat and flour cooked till the mixture becomes blond in color. A blond roux is of light golden brown color as it is at the beginning stage of caramelization.
Equal amounts of fat and flour cooked till the mixture becomes dark brown in color. More caramelized than blond roux, it gives distinct nutty aroma and flavor.
Originally the roux should be like wet cement without any burnt flakes. Avoid burning at the bottom of the pan by constantly stirring the roux. Burnt roux will taste bitter and loose its thickening agent quality. If you doubt that your roux is burnt for some reason, think no further, just discard it and start over again.