The recipe for demi-glace reduces basic brown sauce and brown stock to create a thick sauce. Sachets that contain 1 bay leaf, 1/2 teaspoon of dried thyme and 3 to 4 parsley stems, which are called bouquet garnis, are added to the sauces during cooking and removed later.
First, make the brown stock, which is one of the basic components of the brown sauce. Roast pieces of beef marrow bones in the oven at 450 degrees Fahrenheit for one hour. Coat the bones in 8 ounces of tomato paste, and return them to the pan. Arrange 2 cups of chopped onions, 1 cup of chopped carrot and 1 cup of copped celery on top of the bones, and cook for 30 more minutes. Skim the fat off the top of the liquid. Deglaze the liquid by adding 2 cups of dry red wine to the pan and returning the pan to the heat. Scrape the container with a wooden spoon to remove all the browned pieces.
Once the liquid in the pan is reduced, place everything in a large pot, and add the bouquet garni, salt, pepper and 8 quarts of water. Simmer the liquid four hours, skimming off the fatty top layer as necessary. Strain the stock, and set the liquid aside.
Next, make the brown or Espagnole sauce by melting 1 ounce of clarified butter in a saucepan over medium heat. Add 1/2 cup of diced onions, 1/4 cup of diced carrots and 1/4 cup of diced celery. Sauté the mixture, then gradually stir in 1 ounce of all-purpose flour. Once a paste forms, lower the heat, and cook, stirring off. After 5 minutes, whisk in 3 cups of brown stock and 2 tablespoons of tomato purée, and bring to a boil. Add the bouquet garni, simmering for 50 minutes until the sauce has been reduced.
In a large stock pot, combine the brown stock, Esangole sauce and another bouquet garni, and bring everything to a boil over medium-high heat. Reduce the heat and simmer for 1 1/2 hours until the liquid is reduced. Serve over meat.