Roast the bones (recommended): Arrange bones on a baking sheet and roast at 425°F (220°C) for 30–40 minutes, turning once, until browned. This deepens flavor and color.

Load the slow cooker: Add the roasted bones, onion, carrots, celery, garlic, bay leaves, peppercorns, and any optional herbs or add-ins.

Add vinegar and water: Pour in the vinegar, then add enough cold water to cover the bones by about an inch. Don’t overfill; leave room to gently simmer.

Set and simmer: Cook on Low for 12–24 hours. For a lighter chicken broth, 12–16 hours is great. For beef bones, aim for 18–24 hours. Keep the lid on for consistent heat.

Skim as needed: If foam or excess fat collects on top, skim it off with a spoon. Some fat is fine; you can adjust later.

Strain carefully: Turn off the cooker and let it cool slightly. Use tongs to remove large pieces. Strain through a fine-mesh sieve or cheesecloth into a large bowl or pot.

Season to taste: Add salt gradually once strained, or leave it unsalted if you’ll use it in recipes that already include salt.

Chill and de-fat: Cool quickly (see storage tips below). Once cold, a layer of fat will solidify on top. Remove some or all of the fat for a cleaner taste, or keep a thin layer for protection and flavor.

Store or sip: Transfer to jars or containers. Reheat gently to sip as-is, or use as the base for soups, grains, and sauces.