Demi-Glace

Directions

1. 1
   Melt the butter in a large saucepan over medium-high heat.
2. 2
   Add the onion, carrot, and celery and cook, stirring occasionally, until golden and tender, 8 to 10 minutes.
3. 3
   Add the flour, stirring to coat the vegetables, and cook for 2 minutes.
4. 4
   Add the wine, scraping up any browned bits from the bottom, and cook until evaporated.
5. 5
   Stir in the tomato paste, then add the stock and bouquet garni and bring to a boil.
6. 6
   Position the saucepan so that it is sitting half on the burner.
7. 7
   Simmer over low heat until slightly thickened and reduced by half, about 1 hour, skimming the scum that rises to the surface from time to time.
8. 8
   Strain the sauce through a fine-mesh sieve or several layers of cheesecloth into a heatproof bowl, pressing hard on the solids.
9. 9
   Let the fat rise to the surface and skim off as much as possible.
10. 10
    Return the sauce to the saucepan and simmer over medium heat until reduced to 2 cups, about 10 minutes longer.
11. 11
    Season with salt.