Ingredients:

2 lbs. beef or chicken bones (organic grass fed are best, chicken necks, feet or oxtails can be used also)
3 gallons of cold filtered water
½ cup Braggs Apple Cider Vinegar
1 tablespoon of good sea salt
3 onions, coarsely chopped (optional)
3 celery sticks coarsely chopped (optional)
Several sprigs of fresh thyme tied together (optional)
1 teaspoon diced green peppercorns, crushed (optional)
1 bunch parsley (optional)

Instructions:

Place the bones in a very large stockpot with vinegar and cover with water. Let stand for one hour. Add to the stock pot the vegetables. A large amount of scum (frothy, foamy layer) will come to the top, this needs to be skimmed off with a spoon and discarded. After you have skimmed, reduce heat and add the thyme and peppercorns. Simmer for a least 12 hours and up to 72 hours (I usually do around 24 hours). For the last 10 minutes, add the parsley. A crockpot can also be used to simmer the stock if you are leaving the house for extended periods of time. Remove bones with tongs and discard. Strain the rest of the stock into a large bowl. Let cool in the refrigerator. The stock may turn to gelatin when cooled especially if knuckles are used, this is normal.