Beef Wellington is a British dish of beef tenderloin coated in duxelles, a finely chopped mushroom paste, then wrapped in puff pastry and baked.
It's popularly said to be named after the first Duke of Wellington, Arthur Wellesley, though the story is unconfirmed and the dish's real origin isn't well documented.
The tenderloin is seared before wrapping, and the duxelles layer helps keep the pastry from turning soggy during baking. It's a celebratory, technically demanding dish, usually reserved for holidays and formal dinners and cooked to medium-rare. Variations add foie gras, prosciutto, or truffle to the duxelles, or swap in a different pastry.