Blanch the bones. Divide the bones between two large stockpots and cover with cold water. Bring to a boil over high heat and simmer for 15-20 minutes before draining and rinsing the bones with water.
Roast the bones and the vegetables. Ok, so the bones have been blanched. Now, preheat the oven to 450 degrees F. Transfer the bones and vegetables (carrots, onions, garlic, celery) to the roasting pans. Don't pile them all on top of each other- use two roasting pans. Roast for 30 minutes before gently tossing the bones and vegetables, and roasting for an additional 15-30 minutes more.
Transfer the bones and vegetables back to the stockpots. But not before washing the stockpots first. Make sure you wash your pots after the bones were blanched and drained. Transfer the bones and vegetables back to the stock pots and scrape up any remaining bits and juices remaining in the roasting pan using a metal spatula and a little water, if needed. Transfer to the pot with the bones (don't worry, all those brown bits are FLAVOR!).
Boil the bones. With the bones and vegetables divided between the two pots divide the bay leaves, peppercorns, star anise, cinnamon sticks, and apple cider vinegar between the two pots. Fill each pot with approximately 12 cups water, or until bones are fully submerged. Cover the pots and bring to a low and gently boil.
Simmer the bones. Reduce heat to low and simmer, with the lid slightly ajar, skimming any foam or excess fat, occasionally. Simmer for at least 8-12 hours, ideally 24 hours (do not leave the stove running overnight. Simply cool and store in the refrigerator and continue to simmer the next day). Add more water if needed to make sure bones and vegetables remain fully submerged.
Strain the bones. Once the bones have simmered and your broth is ready, you will need to strain the broth through a fine mesh strainer. Set aside the broth to cool and allow the bones to cool.
Don't forget about the meat. Whether you eat the meat still left on the bones in a bowl of soup or in sandwiches, I can almost guarantee that there is a TON of delicious meat waiting to be picked from the bones. Don't let it go to waste! Discard the meat-free bones and vegetables.
Skim the fat from your broth (optional). Add a couple handfuls of ice to your beef broth to expedite cooling and cover with a lid. Transfer broth to the refrigerator and allow broth to cool fully. The result will be a hard, thick layer of fat and a bottom layer that is your bone broth (which should look like gelatinous brown jello). If desired use a fork to scoop off the top layer of fat. This will leave behind the healthy bone broth, minus the fat.
Store your bone broth. Bone broth stores well in the refrigerator for approximately 5 days. If you make a large batch, I recommend freezing smaller batches in the freezer for up to 6 months (it reheats perfectly!).