To start, preheat the oven to 450º Fahrenheit. Drizzle the oil into a roasting pan large enough to hold the veal bones in a single layer. Place the bones into the pan and roast for about 45 minutes to an hour.

After about 45 minutes check the bones. If they have started to brown and caramelize, flip them over and smear the bones with tomato paste. Roast again for another 15 minutes.

Meanwhile, prepare the vegetables. Wash and roughly chop the carrots, onions, garlic, celery and leeks into roughly 2" -inch pieces. Line a baking tray with aluminum foil, then place the vegetables onto the tray. Drizzle with the remaining oil and toss.

If your oven is big enough to place two trays side by side, then place the vegetables in the oven along with the bones; otherwise, set the vegetables aside while the bones finish roasting.

Once the bones are out of the oven, roast the vegetables for 40 to 50 minutes. Check and stir them after about 20 minutes to make sure they’re getting a nice, even color.

To begin the stock, place the roasted bones into a 10 to 12 quart/liter stock pot. Pour off the excess fat from the roasting pan and discard. Place the roasting pan onto the stove top and over medium heat and deglaze the pan with the red wine. Pour the liquid and all of the sucs (all of the little brown bits) into the stock, along with the bones. Add the roasted vegetables and just enough water to cover all of the ingredients by about 2 to 3 inches. As the stock reduces, you may need to add a bit more cold water to ensure that the bones are always covered.

Next, add the peppercorns, thyme and bay leaves. Bring the stock to a quick boil over medium-high heat, then immediately turn the heat down to low. While the stock simmers, skim the fat and foam off the top, as needed.

After approximately 8 hours, use a slotted spoon to lift out the bones and vegetables. Place them into a strainer that is resting inside another bowl. Strain the liquid through a fine mesh sieve into a clean pot. Discard the bones and vegetables once they have cooled.

Skim the fat from the stock using a ladle or cool the stock and let the fat harden in the refrigerator. Remove it once it has solidified.

To make the demi-glace (or glace de viande), the stock needs to be reduced. Bring the veal stock to a boil and then lower the heat so the stock simmers. Let reduce for about another two hours or until the liquid is reduced by half.

Once it has reduced by half, it should be quite a bit darker and thicker in consistency.

For a smooth demi-glace, strain it one last time, through a fine mesh sieve. If you are not using the demi right away, it is best to pour the demi-glace into a flat casserole dish and and cool.

Once cooled, refrigerate until the demi-glace has set. Then portion the demi-glace into 3 to 4 inch squares and freeze.

Making demi-glace is a big commitment in terms of time, but well worth the effort, as it can be used in many different ways. It will add incredible flavor to your stews and sauces and make them taste that much better.