Preheat oven to 350 degrees and roast the raw bones for 30 minutes. If bones have been cooked, skip this step and roast only the vegetables in Step 2.

Take out of oven and add onions, carrots, and celery. Roast for another 30 minutes.

Place the bones in a large pot (I use pressure cooker) and add water and apple cider vinegar. Let sit for 20 minutes in the cool water.

Rough chop the roasted onions, carrots, and celery and put in the pot with the roasted bones. Add in salt, pepper corns, garlic, and bay leaves.

Bring the broth to boil and simmer for 24-36 hours. If using a pressure cooker, set on the "stew" function and cook for 10 minutes. Allow the pressure to release naturally. Once you can take the lid off, replace with a lid and simmer for 4-6 hours.

Let broth cool and strain using a fine metal strainer to remove all the bits of bone and vegetable.

Remove the fat by slowly sliding a spatula between the fat and the broth. I read that you can save the fat, called "tallow" and use it as fat in other dishes.

Store in refrigerator or freezer.

Note: Sometimes I like to use 4-5 times the vegetables for a different taste. Differences: Step 2 - Instead of roasting the vegetables, heat up the butter and garlic in a large pan. Once the garlic turns light brown, saute the onions, celery, and carrots. See picture below. Add salt, peppercorns, and bayleaves then continue the recipe at Step 5. The broth is more dense and tastes richer. (2nd picture)