Score steak on both sides by making shallow cuts at 1-inch intervals diagonally across steak in a diamond pattern. Using a meat mallet, pound steak into a 10x8-inch rectangle.
Spread mushrooms on top of steak. Roll up meat, starting from one short side. Secure with wooden skewers.
Spray a cold large skillet with nonstick spray coating. In the skillet brown steak roll on all sides. Add vegetable juice cocktail and Worcestershire sauce. Cover and simmer 55 to 60 minutes or until meat is tender, turning steak roll occasionally.
Meanwhile, in a medium saucepan heat the 1-1/2 cups water, onion, and bouillon granules to boiling. Add barley. Cover and simmer for 10 to 12 minutes or until water is absorbed. Remove from heat and stir in parsley.
Transfer roll to a cutting board. Stir together cornstarch and 2 tablespoons water. Stir into liquid in skillet. Cook and stir until thickened and bubbly. Cook and stir 2 minutes more. To serve, remove skewers from meat and slice. Arrange slices on barley mixture. Spoon gravy on top. Makes 4 servings.