Preheat your oven to 400°F (200°C). Place the beef bones on a roasting pan and roast them for about 30-40 minutes, until they are browned.

In a large stockpot, heat a little oil over medium heat. Add the onions, carrots, and celery, sautéing until softened and fragrant, about 5-7 minutes.

Stir in the tomato paste and cook for another 2-3 minutes.

Pour in the red wine and scrape up any browned bits from the bottom of the pot.

Add the roasted bones to the pot along with thyme, bay leaves, and black peppercorns.

Fill the pot with enough water to cover the bones and vegetables by about an inch.

Bring the mixture to a boil, then reduce heat to low and let it simmer gently for 6 hours.

After simmering, use a fine mesh strainer to separate the liquid from the solids.