Place a large piece of heavy-duty foil (21-in. x 17-in.) in a shallow
roasting pan. Place roast on foil. Pour 1 cup water and mushrooms
over roast. Sprinkle with soup mix. Wrap foil around roast; seal
tightly. Bake at 350 degrees F for 2-1/2 to 3 hours or until meat
reaches desired doneness (for medium-rare, a meat thermometer
should read 145 degrees F; medium, 160 degrees F; well-done, 170
degrees F).
Remove roast to a serving platter and keep warm. Pour drippings
and mushrooms into a saucepan. Combine cornstarch and
remaining water until smooth; gradually stir into drippings. Bring to
a boil; cook and stir for 2 minutes or until thickened. Serve with slice
beef