Prime Rib with Mustard and Soy Sauce Au Jus

Prep Time: up to 7 days(dry aging prime rib) + 20 minutes roasting day

Cook Time:  1 hr (oxtails), 20 minutes browning, 45 min / lb, 20 minutes for Au Jus
Makes: About 1 serving / lb

Ingredients:
Prime Rib Roast:

• 1 lb / person Standing rib roast (1 rib will feed two people)
• 1 ½ lbs oxtails
• 1 tablespoon tomato paste
• 3 medium onions, cut into eighths
• 3 tablespoons vegetable oil
• 1 ½ teaspoons kosher salt
• Kitchen Twine
• 1 clove garlic / roast lb - slivered
• 2 tablespoon Olive Oil
• 1 cup Dijon mustard (per 5 lbs of roast)
• ¼ cup soy sauce (per 5 lbs of roast)
• 1 teaspoons / roast lb of Penzy’s English prime rib roast seasoning 

Mustard Au Jus (for 6):

• 1 cup dry red wine
• ¼ cup Dijon mustard
• 1 tablespoon soy sauce
• 1 3/4 cup  low sodium beef stock
• 1 ¾ cup low sodium chicken stock
• 2 sprigs fresh thyme

Directions:

• Dry age the rib roast from 1 to 7 days before cooking the roast.  Put the roast unwrapped on a wire rack over a large pan to catch any drippings.  When you are ready to cook the beef, trim off any dried pieces after the aging.
• Remove the roast from the refrigerator.  Allow roast to reach room temperature by sitting on the counter for several (2-3) hours.
• One hour before roasting the roast: adjust oven rack to lowest position and heat oven to 400 degrees.  Rub oxtails with tomato paste and place in heavy-bottomed, burner-safe roasting pan.  Toss onions with 1 tablespoon oil, and then scatter onions in roasting pan.  Roast until oxtails and onions are browned, about 45 minutes, flipping oxtails halfway through cooking time.  Remove from oven and set roasting pan with oxtails aside; reduce oven temperature to 200 degrees.
• Cut incisions at even intervals in the roast and insert slivers of garlic.
• Heat heavy-bottomed 12 inch skillet over medium heat until hot, about 4 minutes.  Meanwhile, rub ends and fat-side of roast with remaining 2 tablespoons oil, then sprinkle with 1 ½ teaspoons kosher salt and pepper.
• Place roast fat-side down in skillet and cook until well-browned, 12 to 15 minutes; using tongs, stand roast on end and cook until well-browned, about 4 minutes.  Repeat with other end.  DO NOT BROWN WHERE THE RIBS ARE ATTACHED.  Let cool for 10 minutes.
• Tie the roast using kitchen twine; tie the roast parallel to the rib bones at least at each end.
• Mix mustard, soy sauce and Penzy’s English Prime rib spice and spread on the roast.  Place roast brown-side down, pushing oxtails and onions to sides of pan. Stick the probe of the thermometer into the roast so that the probe is approximately in the middle of the roast but not touching a bone.
• Roast until the thermometer reads desired temperature (122 = rare, 130 = medium rare and 145 = medium).  The roasting time is roughly 45 min./ lb.  Remove the roast from the oven.
• Let the roast rest for at least twenty minutes.  Note: the roast will continue to cook while resting – it will increase at least 10 degrees for a 6 to 8 lb roast, more for a larger roast.

Mustard Au Jus: 

• While roast is resting, pour off any extra grease that has collected in the pan.
  Deglaze the pan by pouring in red wine and scrap all browned bits loose.
• Add beef  and chicken broth, thyme and ribs from roast (meaty side down) and bring to a boil.  Turn heat down and reduce by two-thirds (to about 2 cups) 16 to 20 minutes.
• Add any accumulated beef juices.  Discard ribs and oxtails; strain jus through mesh strainer into bowl, pressing on onions to extract as much liquid as possible.
• Whisk in the mustard, soy sauce and pepper.  Pour into gravy boat.