Espagnole sauce is sauce is most commonly used for making demi-glace, although it can also be used as a base to make other recipes such as Beef Stroganoff, Vegetable Beef Soup, and Beef and Mushroom Enchiladas.
Espagnole sauce is a basic brown sauce, and is one of the mother sauces of classic French cooking.
In the early 19th century the chef Antonin Carême included it in his list of the basic sauces of French cooking.
The ingredients to make Espagnole Sauce are.
4 tablespoons unsalted butter.
1/2 medium onion, finely diced.
1 stalk celery, finely diced.
1 carrot, finely diced.
1/4 cup all-purpose flour.
4 cups unsalted or low-salt brown beef stock, preferably homemade.
1/4 cup canned tomato puree.
Pinch salt.
Espagnole sauce is very much meant to be a base sauce and is very rarely used as a sauce on its own.
This is due to its strong and often bitter flavor which is difficult to pair with many dishes.
The hardest sauce to master, espagnole, is also called basic brown or Spanish sauce.
It is made through the creation of a very dark brown roux, to which veal stock or water is added, along with browned bones, pieces of beef, vegetables, brown sugar and various seasonings.
Espagnole is made by thickening brown stock with a roux.
So in that sense, it's similar to a velouté.
The difference is that Espagnole is made with tomato purée and mirepoix for deeper color and flavor.
And, the brown stock itself is made from bones that have first been roasted to add color and flavor.
Velouté is one of the smooth, velvety sauces in French cuisine.
It combines the thickness and structure of a roux as a base sauce, with the more delicate complexity of a white stock.
The stock used for velouté is called white because the bones used to make it are not roasted prior to boiling.