For the Beef Tatar, chop the onion into small cubes. Finely chop anchovy rings and capers. Make a thin mayonnaise from yolks and oil.
Add a dash of Tabasco, Worcestershire sauce and ketchup. Stir in onion, anchovy rings, capers, salt, pepper. Finally, add the very finely chopped. Mix in beef lung roast.
Serve the beef tartar.