Here is the recipe:
4 quarts filtered water
1 1/2 - 2 lbs of bones (beef knuckle bones, marrow bones, meaty bones, chicken or turkey necks, chicken or turkey carcass bones, or any bones you have around)
2 tablespoons apple cider vinegar (organic, unfiltered such as Bragg's brand)
2 teaspoons (or to taste) unrefined sea salt (optional)
Cloves from 1 whole head of fresh garlic, peeled and smashed (optional)
1. Place all ingredients in a 6-quart slow-cooker and set heat to high. Bring to a boil. Once boiling, reduce heat to low and allow to cook for a minimum of 8 hours and up to 24 hours. The longer it cooks, the better! If you do not have a slow-cooker, you can use a pot on the stove. After boiling, set the pot to the lowest flame/setting possible that allows a tiny bubble.
2. After cooking, turn off cooker/pot and allow to cool. Strain through a fine mesh metal strainer or cheese cloth (I did not do this part and it was just fine by me to have bits of meat in my stock/broth!). Place cooled stock/broth in glass jars for the fridge or freezer for later use.
3. Drink as a soup or use as a base in soups, stews, or anything that calls for soup stock!