In the video O'Connell explains how to make the dish and gives us some background information on it.
First strongly season a fillet of beef before frying it in butter and oil to set it, not cook it.
To make the Duxelles fry finely chopped Garlic, Shallots, Thyme and Mushrooms in a pan, but be careful not to cook too long to purée them.
Season the mixture and add Jus, Toasted Panko and Truffle.
Brush the beef fillet with mustard, wrap it tightly in a crepe lined with Duxelles and store it overnight in a fridge to let it set.
The next day wrap the beef fillet in pastry and egg-wash it to give it glaze before putting it back in the fridge for 10 minutes.
Cut the pastry to size and cook until the Wellington reaches 35-degrees.