1. Preheat the oven to 425°F. Place the bones on a baking pan and roast until dark brown, about 45 minutes. Meanwhile, heat the oil in a large, heavy-bottomed pot over medium-high heat. Add onions and cook, stirring, until caramelized, 15–20 minutes. Add the carrots, celery, and garlic and cook until browned, about 15 minutes more.
2. Add the tomato paste and toast until it turns a dark, mahogany color. Add the wine and bring to a boil, scraping up the browned bits from the bottom of the pot. Add the roasted bones, Veal Stock, bay leaf, thyme, and peppercorns. Bring to a boil, reduce the heat, and simmer until the Fond de Veau is rich, dark brown, and reduced by half, about 4 hours. Strain and cool. Store in the freezer in small batches.
