In a large pan over medium-high heat, stir in tomato sauce, lemon juice, and Worcestershire sauce. Stir in parsley, thyme, bay leaves, brown sugar, salt, and red pepper flakes. Add onions and short ribs, and stir together until the mixture comes to a boil.
Cover, reduce heat to medium low, and simmer; stirring occasionally and skimming fat from surface, until meat is tender, about 2 1/2 hours. Remove bay leaves before serving.
