This is just about the same recipe that was in a New York Times article about bone broth.
5 pounds of bones with some meat attached
2 tablespoons olive oil
2 tablespoons tomato paste
¼ cup apple cider vinegar
3 carrots, peeled and coarsely chopped
3 celery stalks, coarsely chopped
2 onions, halved and peeled
2 cups tomatoes – fresh or boxed
1 head garlic cut in half crosswise
2 bay leaves
1 bunch fresh flat-leaf parsley
½ bunch fresh thyme
1 tablespoon black peppercorns
Heat oven to 350 degrees. Place meat and bones in a pan. Coat in olive oil and brush with tomato paste. Roast until browned, 30 to 35 minutes.
Put roasted meat and bones in a 12-quart stockpot and add vinegar and enough cold water to cover by 3 inches. Bring to a boil, then reduce to a low simmer, uncovered, for 2 to 3 hours. While simmering, occasionally skim fat and foam from the top using a ladle.
Add all the remaining ingredients. Continue to simmer, uncovered, for a minimum of 12 hours or up to 72 hours. You can bake it at 200 degrees instead of using the stovetop. I do that if the dogs are in the house. Strain broth. Once broth has cooled, store in the refrigerator in an airtight container.