With a little light olive oil and some of the juice from the anchovies fry the anchovies in a frying pan. Add beef in smallish amounts (about 100g at a time) and seal. Put to one side.
In the same pan add a little more oil and fry onions and capers and a little salt and cook until they just colour. Take out and place with the beef.
Heat oil in pan and slide in mushrooms and fry until coloured, add in Worcestershire sauce and balsamic add onions and beef and combine. Cover and simmer for 15 minutes.
Serve with mash potato and chopped parsley.