In 10 inch skillet combine undrained tomatoes, undrained sauerkraut, applesauce, and brown sugar. Bring to a boil, reduce heat. Add brisket, spooning mixture over the meat. Cover and simmer for 2 1/2 to 3 hours or till meat is tender, spooning sauce occassionally.
Transfer meat to serving platter, keep warm. Skim off fat from pan juices. Combine cold water and cornstarch, stir into tomato mixture. Cook and stir until thickened and bubbly, cook 2 more minutes. Serve as gravy.