A recipe from Bob Zimorino.
Even if you buy a boneless prime rib, I assure you that there were bones in it at some point. Make sure your butcher includes them with your purchase. (There shouldn’t be an additional charge.) You’ll use these bones to make the au jus.
2 medium onions (quartered)
2 large carrots cut into 2 inch pieces
2 large stalks of celery cut into 2 inch pieces
4 unpeeled garlic cloves
3 unpeeled shallot cloves
Toss all of the above together so that the olive oil coats the rest.
Also coat the rib bones and any trim from the roast with olive oil.
Put them together in a roasting pan and roast in a pre-heated oven at 400° for about 45 minutes turning every fifteen minutes or so. The bones should turn brown but not black. Adjust your oven accordingly.
From the oven put them in a large (16 quart) stock pot, fill with cold water to a couple of inches over the bones, then add:
2 sprigs of fresh thyme
6 sprigs of parsley and any extra stems from trimming the leaves
2 bay leaves
About a dozen or so black peppercorns
Deglaze the roasting pan by putting it on the stove top on low heat. Add a cup of red wine (can use water instead). Using a spatula scrape the scraps in the bottom of the pan into the wine and then pour it into the stock pot. Heat the stock to a good simmer (about 200°) but not to a full boil. Cover it, put on the back burner for about the next 4 – 6 hours and let it simmer, periodically skimming the fat off of the top.
When you determine it is ready (at least the 4 hours) strain it through cheese cloth or a fine strainer into another pot, season with salt and pepper to taste. If it doesn’t have a beefy enough flavor you can finish it off with a little beef base (I recommend the brand “Better Than Bullion” but be sure to adjust your salt accordingly because bases are often salty.
Choice two (to buy a mix or au jus base) by the way can be enhanced by skipping the roasting process and just simmering everything and adding beef base to round out the flavor. While it is still good, the roasting of the bones releases the marrow which adds great flavor to your stock.