Heat the oven to 450 degrees F. Spread the bones in a heavy roasting pan and roast for 45 minutes, turning once halfway through, until they're deeply browned.

Transfer the bones to a large stockpot or slow cooker. Deglaze the roasting pan with a splash of water, scraping up the browned bits, and add that to the pot.

Add the vegetables, garlic, herbs and peppercorns, then cover everything with water by about 2 inches.

Bring it to a boil, then drop the heat to a bare simmer and cook for 4 to 24 hours. Never let it boil hard or the broth will be cloudy. Add water as needed to keep the bones covered.

Lift out the bones, then strain the broth through a fine mesh strainer lined with cheesecloth. Let it drain on its own without pressing on the solids. Discard the solids.

Skim the fat off, or chill the broth and lift off the fat cap. The broth must go into the jars strained and skimmed, with no solids.

Prepare a pressure canner for a hot pack: rack in the bottom, 2 inches of water, brought to a gentle simmer. Heat the jars.

Reheat the strained broth to a boil, then turn off the heat.

Ladle the hot broth into hot jars, leaving 1 inch headspace. Remove air bubbles, adjust the headspace, wipe the rims and cap with two-part canning lids at fingertip tight.

Load the jars, lock the canner lid, and vent a steady stream of steam for 10 minutes before adding the weight.

Process pints for 20 minutes or quarts for 25 minutes, at 10 pounds pressure on a weighted gauge canner or 11 pounds on a dial gauge, adjusting the pressure for altitude (see notes).

Turn off the heat and let the canner return to zero pressure on its own. Wait 5 minutes, remove the lid, then let the jars stand in the canner 10 minutes before lifting them out.

Cool the jars undisturbed for 12 to 24 hours, then check the seals, label and store.