Preheat the oven to 475 degrees F.

Place the veal bones in a large roasting pan, being sure that they all rest in a single layer. If you cannot fit all the bones in a single layer, roast them in batches. Place the roasting pan in the oven and roast the bones for about 1 hour, turning the bones periodically to ensure even browning. Remove the pan from the oven and pour off and reserve the fat. Place the bones in a large 3 gallon stockpot. Place the roasting pan on the stove over a medium heat and add 2 tablespoons of the reserved fat to the pan. Add the onions, carrots, celery and garlic to the pan and cook, stirring frequently, until the vegetables are lightly caramelized, about 10 minutes. Add the tomato paste to the roasting pan, stir to incorporate, and continue to cook another 10 minutes, or until the vegetables are a deep amber color. Add the red wine to the pan to deglaze, scraping the bottom of the roasting pan with a wooden spoon to loosen the browned bits. Pour the contents of the roasting pan into the stockpot and cover with the water and sachet.

Bring the stockpot to a boil then reduce to a simmer. Allow stock to simmer for 8 to 10 hours, skimming the scum and fat that will rise to the top frequently. If at any point the water level falls below the bones, add water so that the bones remain submerged. It is not unusual to have to add up to 3 quarts of additional water during the 8 hours of simmering, adding the water a quart at a time to the stockpot. When the stock has simmered for the full 8 hours, remove from the heat and strain through a fine mesh sieve lined with cheesecloth. Refrigerate or freeze whatever is not used. Alternately, the stock can be returned to the stove and reduced by 1/2 or more for easier storage.