Espagnole (pronounced like the word for Spanish: "español") is a basic brown sauce that is one of the five mother sauces of classical cuisine. It's also the starting point for a rich and deeply flavorful sauce called demi-glace, which is traditionally served with red meats.
Making espagnole sauce is not too different from making velouté — they're both essentially a stock-based sauces thickened with roux. Where they differ is that espagnole is made with brown stock, and it includes additional ingredients, such as tomato purée (which adds color and acidity) and mirepoix, which is a fancy name for chopped up carrots, celery and onions, which add a tremendous amount of flavor and aroma.
You'll also see something called a sachet, which is simply a few dried herbs and spices tied up in a cheesecloth bundle to make it easy to fish it out afterward.
To make demi-glace, you'd combine equal parts espagnole and brown stock (i.e. beef stock) along with additional mirepoix (and probably another sachet) and reduce it by half (hence demi). Here's a shortcut method.
- ½ cup onions, diced
- ¼ cup carrots, diced
- ¼ cup celery, diced
- 1 oz clarified butter
- 1 oz all-purpose flour
- 3 cups brown stock (i.e. beef stock)
- 2 Tbsp tomato purée
- 1 bay leaf
- ½ tsp dried thyme
- 3–4 fresh parsley stems
- 7–8 whole black peppercorns
- Fold the bay leaf, thyme, parley stems and peppercorns in a square of cheese cloth, and tie the corners with a piece of kitchen twine. Leave the string long enough so that you can tie it to the handle of your pot to make it easier to retrieve it.
- In a heavy-bottomed saucepan, melt the butter over a medium heat until it becomes frothy.
- Add the mirepoix and sauté for a few minutes until it's lightly browned. Don't let it burn, though.
- With a wooden spoon, stir the flour into the mirepoix a little bit at a time, until it is fully incorporated and forms a thick paste (this is your roux). Lower the heat and cook the roux for another five minutes or so, until it just starts to take on a very light brown color. Don't let it burn, though!
- Using a wire whisk, slowly add the stock and tomato purée to the roux, whisking vigorously to make sure it's free of lumps.
- Bring to a boil, lower heat, add the sachet and simmer for about 50 minutes or until the total volume has reduced by about one-third, stirring frequently to make sure the sauce doesn't scorch at the bottom of the pan. Use a ladle to skim off any impurities that rise to the surface.
- Remove the sauce from the heat and retrieve the sachet. For an extra smooth consistency, carefully pour the sauce through a wire mesh strainer lined with a piece of cheesecloth.
- Serve hot. If not serving the sauce right away, keep it covered and warm until you're ready to use it.