In a large skillet, brown pork in butter on both sides over medium heat. Remove and keep warm. Set aside 1/4 cup of broth. In the same skillet, add the potatoes, mustard, Worcestershire sauce, salt, pepper and remaining broth. Bring to a boil. Reduce heat; cover and simmer for 15-17 minutes or until the potatoes are tender.
Stir in the mushrooms, onions and pork. Cover and simmer for 5 minutes longer or until meat is no longer pink.
In a small bowl, combine the flour and reserved broth until smooth. Gradually stir into pork mixture. Bring to a boil; cook and stir for 2 minutes or until thickened.