01 - Preheat oven to 425°F. Place beef bones and shank or oxtail on a roasting pan. Roast for 30 to 40 minutes, turning once, until deeply browned.
02 - Move roasted bones and meat into a large stockpot. Pour off and discard any fat from the roasting pan.
03 - In the same roasting pan, toss onions, carrots, celery, and leek with tomato paste and vegetable oil. Roast for 15 to 20 minutes until caramelized. Transfer to stockpot.
04 - Pour a small amount of water into the roasting pan, scrape up browned bits, then add this liquid to the stockpot.
05 - Incorporate garlic, bay leaves, peppercorns, thyme, parsley, and cloves into the pot.
06 - Add cold water to cover all ingredients. Bring to a gentle simmer over medium heat without boiling.
07 - Reduce heat to low and simmer uncovered for 4 hours, occasionally skimming off scum and fat.
08 - Strain the liquid through a fine-mesh sieve or cheesecloth into a clean pot or bowl. Discard solids.
09 - Let stock cool, then refrigerate. Remove any solidified fat from the surface before use.
10 - Add salt to taste just before serving or incorporating into dishes.