You can get bones from the meat counter at the supermarket (knuckle, neck, or marrow bones) to use for bone broth. Call ahead to have the butcher set them aside for you. Or save the ones left from roasts, steaks (think T-bone), and roasted chicken or turkey carcasses. Pack the bones in resealable plastic freezer bags and freeze up to 3 months. (Freeze vegetable scraps for broth the same way.)
Roasting the bones adds color and flavor to the finished broth. If there are any crusty bits stuck to the pan, add some water and scrape them up with a wooden spoon or whisk. Stir them into the broth to simmmer, where they will add concentrated flavor and color.
Place the roasted bones in a large stockpot, slow cooker, or pressure cooker. Add vegetables, seasonings, and water. Simmer as directed to draw flavor and minerals from the bones and veggies.
After simmering, cool broth slightly and strain through a sieve or colander lined with cheesecloth. This traps small particles, resulting in a clearer broth. You might notice that homemade broth isn't as deeply colored as purchased broth. This is because purchased broth often has caramel coloring added.
Remove the fat to get the clearest broth with the best nutrition. The easiest way is to chill the broth first. The fat will harden on the surface of the broth, so it is simple to lift it off with a slotted spoon and discard.
There are three ways to simmer bone broth, each with its own pros and cons.
1. Stovetop: When simmering broth in a stockpot on the stove, more evaporation occurs than with the other two options. This can help boost flavor, but the volume will be reduced. You'll have to keep a close eye on it, which can be tedious over a 12-hour cooking period.
2. Slow Cooker: No need to babysit this one. Set the timer and let the cooker do the rest. There will be no evaporation of liquid, so the volume that goes into the cooker is the volume that comes out. However, you can't make as much in a slow cooker because it's smaller than a stockpot. You'll need to halve the recipe.
3. Pressure Cooker: If you have a pressure cooker, you can cut cooking time from 12 hours to 2 hours and still get broth with the same rich flavor as the stovetop method. As with slow cookers, you can only make half as much.
To freeze broth, ladle cooled broth into freezer containers (leave 1-inch headspace) or resealable plastic freezer bags. Cover or seal. Lay bags flat in freezer. Freeze up to 6 months. Thaw in the refrigerator.