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 to a large stockpot. Pour off any fat from roasting pan and discard.
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. Add vegetables to stockpot.
04 - Pour a small amount of water into roasting pan, scraping browned bits, and add this liquid to the stockpot.
05 - Add garlic, bay leaves, peppercorns, thyme, parsley, and cloves to the stockpot.
06 - Pour cold water over ingredients in stockpot until fully submerged. Bring to a gentle simmer over medium heat without boiling.
07 - Lower heat to low and simmer uncovered for 4 hours, skimming off any scum or fat occasionally.
08 - Strain stock through a fine-mesh sieve or cheesecloth into a clean container. Discard solids.
09 - Allow stock to cool before refrigerating. Skim off any solidified fat from the surface before use.
10 - Add salt to taste before serving or incorporating into other preparations.