A recipe
Bones, water, and a long slow simmer — the plain stock behind soups, broths, and sauces. No mysticism, no ferment, just time on the stove.
Cool it fast and refrigerate within two hours — bacteria multiply quickest in the hours a warm pot sits out. Reboiling kills most bacteria but not toxins some leave behind, so it won't save broth that's been out too long or smells off. Any sour smell, grey-green tint, or sliminess means throw it out. If you're pregnant, immune-compromised, or unsure, ask a doctor.
In the fridge, in a sealed container, for up to four days. Freeze for longer storage.
Low and slow, and never unattended.