One good recipe for boneless prime rib roast is boneless garlic and rosemary rubbed prime rib with red-wine mushroom sauce. To prepare the rib-eye, allow one 5-pound rib-eye to rest at room temperature for two hours. Preheat the oven to 250 degrees Fahrenheit.
Rub the roast with 2 tablespoons of olive oil, 1 tablespoon of salt and 2 tablespoons of ground black pepper to coat. Cook the roast in a skillet over medium-high heat until all sides are browned, approximately 10 minutes. Allow the roast to cool slightly, and then rub it with 8 minced large cloves of garlic and 2 tablespoons of minced fresh rosemary.
Pour out the pan drippings, reserving about 2 tablespoons in the pan. Cook two 8-ounce packages of sliced baby bella or white mushrooms until they are soft, approximately eight minutes. Pour in 1 cup of chicken broth and 3/4 cup of red wine, and add 1 tablespoon of Dijon mustard. Allow the sauce to simmer and reduce for about three minutes. Remove the sauce from the heat, and set it aside.
Bake the roast in the oven until an internal thermometer reads 135 degrees Fahrenheit for medium-rare or 140 degrees for medium doneness. When ready to serve, reheat the sauce over medium-high heat, and add 2 teaspoons of cornstarch. Cook the sauce for approximately one minute, or until slightly thick. Slice the roast, and serve it with the warm sauce.