What is beef welington?

Answer 1

The basic recipe is a fillet of beef, wrapped in puff pastry and then baked. Most versions of the dish coat the beef in a layer of finely chopped and sauted mushrooms or in some cases a layer of pate before wrapping in the pastry.

Some say that it was Duke Wellington's favorite dish, and hence is called Beef Wellington. Others say it is of Irish decent, from a dish called steig Wellington of Ireland. The French even have a version somewhat similar called "fillet de boeuf en croute".