Step 1

Set a large 6 to 8 quart sauce pot over medium heat. Add the butter, chopped carrots, onions, celery, and garlic to the pot. Stir and sauté for 10 minutes to soften the vegetables. Then sprinkle the flour into the pot. Continue to stir and sauté the vegetables, creating a roux, until the roux is golden and smells toasty, about five more minutes. At this point the vegetables should be very soft.

Step 2

Pour in the beef stock, followed by the bay leaves, whole black peppercorns, tomato purée, and salt. Stir well, scraping the bottom of the pot.

Step 3

Bring to a simmer, then lower the heat if needed and continue to simmer for 30 to 45 minutes, until the mixture has reduced to 1/3 of its original size. (You can leave the Espagnole sauce thinner, or cook it down to a gravy consistency. This is just a matter of personal preference or planned usage.)

Step 4

Set a mesh strainer over a large bowl. Ladle the sauce base into the strainer to remove all vegetable chunks and spices. The sauce should be smooth and fine. Taste, then salt as needed.

Step 5

To Make Demi Glace: Set a clean pot over medium heat. Add 2 cups of Espagnole Sauce to the pot, followed by one cup of beef broth, one cup of wine or dry sherry, and a teaspoon of fresh thyme leaves.

Step 6

Bring to a simmer, then reduce the heat a little and continue to simmer for 15 to 20 minutes, until the mixture has reduced by half. Taste, then salt and pepper as needed.

Step 7

Set a fine mesh strainer over a bowl and pour the demi-glace through the strainer to remove any debris, so that the demi-glace is very smooth.