01 - For deeper flavor and richer color, arrange beef bones on a roasting pan and roast at 400°F for 30 minutes before proceeding. This step is optional but highly recommended.
02 - Place the beef bones in a large stockpot or slow cooker. Add the roughly chopped carrots, celery, quartered onion, smashed garlic, bay leaves, fresh parsley, and whole peppercorns.
03 - Pour in the apple cider vinegar and cold water, ensuring all bones and vegetables are fully submerged.
04 - Bring to a gentle simmer over medium heat. During the first hour, use a skimmer or ladle to remove any foam or impurities that rise to the surface.
05 - Reduce heat to low and simmer uncovered or partially covered for at least 12 hours. Periodically check and add water as needed to keep the bones submerged. The longer the simmer, the richer and more gelatinous the result.
06 - Strain the broth through a fine-mesh sieve or cheesecloth into a clean container. Discard all solids. Season with salt to taste.
07 - Allow the broth to cool, then refrigerate. Once chilled, the fat will solidify on the surface — skim it off if desired. Store refrigerated for up to 5 days or freeze for up to 3 months.