This is a basic building block when making several sauces in your own kitchen. Roux is a thickening agent produced from flour and fat. Traditionally the flour is from wheat and the fat is clarified butter but these days the world is your oyster – or so they say. So there is a lot of traditional as well as modern day flexibility.
Roux is the base of three of Escoffier’s Mother Sauces: béchamel sauce, velouté sauce and espagnole sauce. It’s what you add to the roux that will distinguish each of the above sauces. Roux can be white, brown or nearly black (not burned) to create various sauces as well. For the white sauces (béchamel and Velouté) the roux is not browned and remains white but for espagnole the roux is browned.
The fat used as I mentioned is typically clarified butter but as long as it is fat it can be used. So butter, vegetable oil, lard and drippings from bacon can be used depending how you are going to use the roux. Drippings from bacon or from cooking pork, chicken, beef and so on in fat (oil, butter, etc) can be used to make a gravy or soup.
The flour is most often from wheat but with the growing amount of gluten intolerance there are many chefs having wonderful success with rice flour as well as other gluten free flours. It isn’t difficult to make a small batch of roux from your favorite flour to see how well it works for your roux.
The fundamental rule of thumb for making roux is equal parts flour and fat. To create thinner or thicker roux I like Julia Child’s table 1 (which is based on American all-purpose wheat flour):
Thin Sauce or Soup 1 TBL per cup of liquid
Medium, General-Purpose Sauce 1 ½ TBL per cup of liquid
Thick Sauce 2 TBL per cup of liquid
Soufflé Base 3 TBL per cup of liquid
1 Mastering the Art of French Cooking – Julia Child, Louisette Bertholle, Simone Beck
2 TBL Flour
2 TBL Butter 2
2 Clarifying butter removes the particulates that would cause it to burn and taste unpleasant.
In a heavy bottomed sauce pan, melt the butter over low heat. Once the butter is melted add the flour while whisking and still over low heat. Stir the butter and flour until all is incorporated together. Allow to cook on low heat for a couple of minutes.
You now have a white roux.
In a heavy bottomed sauce pan, melt the butter over low heat. Allow the butter more time to begin to darken. Once the butter has begun to darken add the flour while whisking and still over low heat. Stir the butter and flour until all is incorporated together. Allow to cook on low heat until the roux is a nut brown. Have patience and do this over low heat to ensure it is perfect and does not burn. To create an even darker roux continue cooking until it reaches the desired color you want – be vigilant to keep it from burning.
You now have a brown roux.