Rub the meat with salt & pepper,cover in foil and rest overnight in fridge..
Coat bottom of a heavy skillet with olive oil. Once pan is nearly smoking Sear tenderloin until well-browned on all sides, about 5 mins per side.
Transfer to a plate. When cool enough coat all sides with mustard.set aside.
To make Duxelles(mushroom sauce): In a food processor, pulse mushrooms, shallots, and thyme until finely chopped.
To skillet, add butter and melt over medium heat. Add mushroom mixture and cook until liquid has evaporated, about 10 - 15 minutes. Season with salt and pepper, let it cool..
Place plastic wrap down on a work surface, overlapping so that its twice the length and width of the tenderloin.
Arrange the bacon strips on the plastic wrap into a rectangle thats big enough to cover the whole tenderloin. Spread the duxelles(mushroom sauce) evenly and thinly over the bacon strips.
Now place the tenderloin on this and roll meat into the bacon-mushroom mixture, using plastic wrap to roll tightly. Tuck ends of bacon as you roll, then twist ends of plastic wrap tightly into a log and transfer to fridge to chill (this helps it maintain its shape).
Heat oven to 250c... Lightly flour your work surface, then spread out the prepared puff pastry and roll it into a rectangle that will cover the tenderloin. Remove tenderloin from plastic wrap and place on bottom of puff pastry. Brush the other three edges of the pastry with egg wash, then tightly roll beef into pastry.
Once the log is fully covered in puff pastry, trim any extra pastry, then crimp edges with a fork to seal well.
Wrap roll to get a really tight cylinder, then chill for 20 minutes.
Remove wrap, then transfer roll to a foil-lined baking sheet. Brush with egg wash..
Bake until pastry is golden, about 40 to 45 minutes. Let rest 10 minutes before carving and serving...
Enjoy with a glass of your favourite Red Wine. BonAppetit
