Demi-Glace

Preheat the oven to 450 degrees F.

Pour the oil into a metal roasting pan and put it in the preheated oven for 3 to 5 minutes to heat up the pan and condition it with the oil. Spread the bones out on the roasting pan and cook until browned, 30 to 45 minutes, turning the bones occasionally so they brown evenly.

Transfer the bones to a large-enough stockpot to accommodate the bones, 6 quarts ice water and more. Use tongs to transfer the bones so you do not pour any fat into the stockpot. Add the ice water to the stockpot and bring to a simmer. Allow the stock to cook for 4 hours at a slow simmer. Skim the surface of the stock occasionally to remove any fat or impurities.

While the stock is simmering, discard all but about 1/4 cup of the fat from the roasting pan. Bring the pan back up to temperature over high heat on the stovetop. Add the onions and carrots and cook until golden brown and caramelized. Add the celery and cook for another 10 minutes. Stir in the tomato paste, thyme and bay leaf and cook, stirring regularly, until the tomato paste gets a brick red color, about 15 minutes. Add 1 cup of the red wine and stir it into the mirepoix (vegetable) mixture.

Add the mirepoix mixture to the stock after the 4-hour simmering time. Bring the stock back up to a simmer and continue to cook it for another 2 hours.

In a separate pot, bring the remaining 7 cups red wine to a boil and cook until reduced by half, 15 to 20 minutes.

When the stock has simmered for 6 hours, strain it through a chinois and combine the strained stock with the reduced red wine. Bring the stock to a boil, lower the heat to a hard simmer and reduce the stock until it has a consistency that coats the back of spoon and is about 2 quarts (8 cups) in volume, up to 1 hour. Season with salt and pepper and then strain the sauce though a chinois again.