my version -- with chestnuts, spinach, mushrooms, and kalamata olives -- served with demi-glace sauce; pearl onion and pickled beets; stuffed zucchini; glazed carrots; and arugula, radish salad...
"Beef Wellington is an English dish made of fillet steak coated with pâté and duxelles, wrapped in puff pastry, then baked. Some recipes include wrapping the coated meat in a crêpe or parma ham to retain the moisture and prevent it from making the pastry soggy." -- Wikipedia
Example of Duxelles: "Add mushrooms, shallots, garlic, and thyme to a food processor and pulse until finely chopped. Add butter and olive oil to a large saute pan and set over medium heat. Add the shallot and mushroom mixture and saute for 8 to 10 minutes until most of the liquid has evaporated. Season with salt and pepper and set aside to cool."
"The chateaubriand is cut from the tenderloin, which is part of the loin primal. This is the same sub-primal as the filet mignon, the origin of the most tender steak cut. ... The tenderloin can be sliced into filet mignon steaks or left whole and trimmed into a chateaubriand roast – a roast-size filet mignon."
"Demi-glace is a rich brown sauce in French cuisine used by itself or as a base for other sauces. The term comes from the French word glace, which, when used in reference to a sauce, means "icing" or "glaze." It is traditionally made by combining one part Espagnole sauce and one part brown stock." -- Wikipedia