Instructions

• Put the mushrooms into a food processor with some seasoning and pulse to a rough paste
• Scrape the paste into a pan and cook over a high heat for about 10 mins, tossing frequently, to cook out the moisture from the mushrooms
• Spread out on a plate to cool
• Heat in a frying pan and add a little olive oil
• Season the beef and sear in the hot pan for 30 secs only on each side
• (You don't want to cook it at this stage, just colour it)
• Remove the beef from the pan and leave to cool, then brush all over with the mustard
• Lay a sheet of cling film on a work surface and arrange the Parma ham slices on it, in slightly overlapping rows
• With a palette knife, spread the mushroom paste over the ham, then place the seared beef fillet in the middle
• Keeping a tight hold of the cling film from the edge, neatly roll the Parma ham and mushrooms around the beef to form a tight barrel shape
• Twist the ends of the cling film to secure
• Chill for 15-20 mins to allow the beef to set and keep its shape
• Roll out the puff pastry on a floured surface to a large rectangle, the thickness of a £1 coin
• Remove the cling film from the beef, then lay in the centre
• Brush the surrounding pastry with egg yolk
• Fold the ends over, the wrap the pastry around the beef, cutting off any excess
• Turn over, so the seam is underneath, and place on a baking sheet
• Brush over all the pastry with egg and chill for about 15 mins to let the pastry rest
• Heat the oven to 200C, 400F, gas 6
• Lightly score the pastry at 1cm intervals and glaze again with beaten egg yolk
• Bake for 20 minutes, then lower the oven setting to 180C, 350F, gas 4 and cook for another 15 mins
• Allow to rest for 10-15 mins before slicing and serving with the side dishes of your choice
• The beef should still be pink in the centre when you serve it