Pre-heat the oven to 500° F (260° C). Line a roasting pan with aluminum foil. Rinse the roast, pat it dry, and bring to room temperature. Sprinkle with the Worcestershire sauce and seasoned pepper.
In a bowl add 10 cups of kosher salt, Italian dressing mix, and egg whites and stir to combine. Sprinkle water over the top of the salt mixture until it is well-moistened, but not wet.
Place a 1/2" layer of the salt mixture in the middle of the roasting pan, slightly larger than the diameter of the roast. Place the roast, fat side up, on top of the salt. Insert a meat thermometer into the center of the roast. Carefully pack the remaining salt mixture onto the meat, covering it completely.
Place the roast in the oven and reduce the temperature to 425° F (220° C). Roast for 14 to 16 minutes per pound, or until the thermometer reads 5° F less than desired temperature. Final temperature for rare will be 130° F; 135° F for medium rare; 140° F for medium.
Remove the roast from the oven and let it rest for 5 minutes.
For jus, in a small saucepan over medium heat, add the beef broth and bring it to a boil. Reduce the heat, add the soup mix, and simmer for 5 minutes. Remove from the heat.
Remove the salt crust from the roast by breaking it and peeling it away. You may need a hammer.
Cut into individual slices and serve with vegetables.
There are 374 calories in 1 serving of Christmas Prime Rib.