Place pot roast in center of double thickness of heavy duty aluminum foil. Sprinkle all sides of meat with soup mix. Add potatoes and carrots around meat. Spoon cream of mushroom soup on top. Seal meat in foil. Place in 13x9x2 inch pan. Bake at 350 degrees for 2 1/2 to 3 hours. Remove meat to platter. Skim off excess fat from meat juices. Serve juices with meat or thicken for gravy.