Prime rib roast can be pricey, so it's worthwhile to cook down the bones into a rich soup stock to use as a base for a few more meals. Making beef stock takes time but very little effort. You simply cover the rib bones, a few cups of vegetables and a handful of herbs with water and allow the stock to cook to full flavor. One of the benefits of making your own stock is that you can control the ingredients. By skimming away fat and using herbs instead of salt, you'll keep the fat and sodium content low. The simmering stock will fill every corner of your house with a delicious aroma too.
Trim four or five ribs from a prime rib roast and place them in the bottom of a large stock pot. Cover the ribs completely with water and cover the pot with a lid. Simmer the meat until it is tender and falling off the bones. Take the pot off the stove and allow it to cool.
Skim the fat off the top of the stock with a large spoon and discard. Scoop the ribs and rib meat from the pot using a large slotted spoon. Return the ribs to the pot and store the meat in the refrigerator for later use.
Prepare vegetables for the stock. Celery, onions, carrots and garlic are all flavorful options. The vegetables will be removed and discarded, so you don't need to do a lot of chopping. Rinse the celery and carrots and cut off the tops with a sharp knife. Remove the outside, papery skin from the onion and chop it into quarters. Put the celery, carrots, onions and whole cloves of garlic in the pot with the rib bones.
Add herbs. Whole peppercorns, bay leaves, oregano and basil make a tasty stock, but don't overseason. If you're using the stock in another recipe, you don't want the flavor to be overpowering. Experiment with other seasonings such as garlic, thyme and rosemary.
Return the pot to the stove and add enough water to cover the ribs and vegetables by 2 inches. Bring the stock to a boil, then reduce the heat and simmer for several hours.
Cool the stock in the refrigerator. Skim away any remaining fat. Remove the bones and vegetables with a slotted spoon and discard.