How to Render your own Tallow
Start with your beef fat. Cut off pieces of meat on the fat and remove the silver skin (thin lining around the meat and fat). You are looking for the thick, rubbery, pure white fat.
Using a large crock with lid, place your pure fat over low heat. In the winters, we will put this on the wood stove. Let simmer (bubbling but not burning) for 6-8 hours. As long as it's not burning, it is rendering more tallow out of your fat. Heat until there are only hard, golden crumbles left.
Filter out the crumbles through cheesecloth and pour your tallow into clean, glass mason jars. Allow to cool, and place in refrigerator to keep for 6 months, or use immediately at room temperature (it will last at room temperature for a few months or longer depending on how pure it is, but longer in colder temperatures).
A package of around 5 lbs. of fat will render two to three quarts of tallow.