In a large cook pot place undrained tomatoes, sauerkraut with applesauce and brown sugar.
Bring to a boil.
Lower heat and add brisket so that mixture can cover some of brisket.Cover and simmer until meat is fork tender ( about 3 hours ); spooning sauce over brisket intermittently.
When meat is done, place brisket on serving platter.
Remove excess fat from pot. Season sauce to taste ( more sugar, spices etc. ). Thicken if desired with a bit of cornstarch mixed with some cold water and add to sauce and cook and stir till thickened.
For best serving, prepare brisket ahead of time, let cool completely, slice meat, cover with sauce and refrigerate till needed ( may be frozen ). Gently reheat and serve slices of meat and sauce.