Dissolve 1 Tbsp brown sugar in 2 Tbsp Worcestershire sauce in a casserole dish, add 1 can tomatoes.
Coat topside steak pieces in ~ 1/4 cup flour seasoned with 1 Tbsp dry mustard & S+P.
Chop 1 onion finely, & brown in a frying pan. Add seasoned steak pieces & fry until browned. Add onions & steak to casserole dish.
Bake 150oC/300oF 1 1/2 hours.