Preheat oven to 450°F (convection on)
Lightly oil beef bones and roast 30–45 minutes, until deeply golden brown
In a large stockpot over high heat, add 1 tbsp beef tallow
Add carrots, onions, celery, and garlic. Cook, stirring well, until lightly caramelized
Stir in tomato paste and cook 1–2 minutes
Deglaze with red wine and reduce by about half
Add roasted bones, thyme, bay leaf, parsley stems, and black peppercorns
Cover with water just enough to submerge the bones
Bring to a gentle simmer and cook 8–9 hours, skimming impurities as they rise
Strain the stock and let cool completely
Once cold, remove and discard the hardened fat
Return stock to a pot and reduce by ⅓ to ½, until dark, glossy, and gelatin-rich
