Beef Bone Broth

Simply place a big bunch of beef marrow bones in a crock-pot or a big stockpot, cover them with cold water and set the temperature on low heat so it doesn’t do much more than simmer.
Add 2 tablespoons of apple cider vinegar to the cold water to help draw the nutrients from the bones.
You can roast your beef bones beforehand for 25-30 minutes at about 375oF (190oC) and then use them to make your stock. This technique makes a much darker stock with a roasted flavor.
Allow to simmer to 6 to 48 hours, but continue to add water as it evaporates.