My wife asked me whether I have an idea for holiday recipe. I prefer beef, so I suggested Prime Rib Roast. But the problem is, she never made it before. Well, I tried to help her, so I browsed the internet and found this perfect prime rib recipe written by Judy2river. Here it is. Ingredients 1 (6 pound) boneless prime rib roast 2 tablespoons prepared horseradish 2 tablespoons Dijon mustard 2 teaspoons kosher salt 2 teaspoons coarsely ground black pepper 2 teaspoons dried thyme 2 teaspoons garlic powder 2 stalks celery, cut into 2-inch pieces 1 carrot, cut into 2-inch pieces 1 small unpeeled onion, quartered and separated 2 teaspoons concentrated beef base (paste) 1 1/2 cups water 1 teaspoon cornstarch