Quickly sear the meat on a pan, no more than 15 seconds on each side.

Season the meat with a little salt and pepper.

Vacuum pack the meat and cook it sous vide/water bath at 54 degrees Celsius (129 degrees Fahrenheit) for 2 hours.

Remove the meat from the water bath and dry it thoroughly.

Place the meat in a freezer for about 30 minutes to make sure it doesn't continue cooking in the oven afterwards.

 

Start by finely chopping the onion and mushrooms. 

Dry fry them on medium-high heat until the liquid disappears and it becomes shriveled and dry. This can easily take 30 minutes.

Blend the contents and it's ready for your Beef Wellington.

Roll the puff pastry sheets together two by two, so they are suitable to wrap the meat.

Take the meat out of the freezer and brush it with mustard. Roll out the puff pastry on baking paper and lay the Parma ham on top. Place the mushroom mixture on top and then the meat. See a more comprehensive picture series here.

Wrap the puff pastry around and make a few cuts in the top so that the heat can escape from the "bread".

Give it 10 minutes at 200 degrees Celsius (392 degrees Fahrenheit) fan oven. It can be a little shorter or longer time, it’s about getting the puff pastry to have a little color.