4-5 pounds beef bones (from grass-fed beef is best)
1/3 c. raw apple cider vinegar
3 large carrots (organic), rough chopped
3 ribs celery (organic), rough chopped
1 large yellow onion (organic), rough chopped
Add bones and vinegar to 12-quart stock pot. Fill with filtered-water to approximately 4-5 inches from the rim. Let the bones and vinegar soak in water for 1 hour to allow the vinegar to draw minerals from the bones.
Bring stock to boil over high heat. Lower heat; simmer stock for 24 hours. Be sure to keep the stock at a continuous light boil. You will see at least one “gurgle” continuously rise to the surface of the stock.
After 24 hours, add the vegetables and continue to boil for an additional 24 hours.
After 48 hours, remove the bones and discard. You may also wish to reserve the liquid from the vegetables. With the vegetables in the strainer, gently squeeze the vegetables by pressing a large serving spoon against them catching the liquid back into the stock pot. Then, strain stock through a metal strainer into mason jars or heat-resistant, freezer-safe bowls/containers.
When the stock has completely cooled, you may wish to remove the fat that will float/harden on the surface. Marrow stock will have a very thick layer of fat. Be sure to leave at least a small amount in your stock. Cover mason jars or bowls of stock and store in refrigerator or freezer.