01 - Arrange beef bones on a rimmed baking sheet and roast at 400°F for 30 minutes until deeply browned, turning once halfway through. This step is optional but builds significantly richer flavor and darker color.
02 - Transfer bones to a large stockpot or slow cooker. Add chopped carrots, celery, quartered onion, smashed garlic, bay leaves, parsley, and whole peppercorns. Pour in apple cider vinegar and cold water, ensuring all bones and vegetables are fully submerged.
03 - Set over medium heat and bring to a gentle simmer. During the first hour, use a skimmer or ladle to remove foam and impurities that rise to the surface. This ensures a cleaner, clearer finished broth.
04 - Reduce heat to the lowest setting. Simmer uncovered or partially covered for 12 hours, checking periodically and adding small amounts of water as needed to keep bones submerged. The extended cook time draws maximum collagen and minerals from the bones.
05 - Remove pot from heat. Strain broth through a fine-mesh sieve lined with cheesecloth into a large bowl or second pot. Discard all spent solids — the bones, vegetables, and aromatics have given their flavor.
06 - Season the strained broth with kosher salt to taste. Start conservatively — you can always add more, but you cannot remove it.
07 - Allow broth to cool to room temperature, then refrigerate. Once chilled, fat will solidify on the surface and can be easily lifted off with a spoon if desired. Store refrigerated for up to 5 days, or freeze in airtight containers for up to 3 months.