Instructions

1. Wrap the beef fillet well in cling film and place in the freezer for 1 hour, or until the outside is beginning to firm up. (This will make it easier to cut thin slices.)
2. Meanwhile, to make the dressing, peel and finely grate into a bowl enough horseradish to give you 1 tbsp, or more if you prefer a hotter dressing. Add the crème fraîche with the wine vinegar and salt and pepper to taste. Stir to combine and leave to infuse for 30 minutes. Add a little water to make the dressing liquid enough to drizzle, then taste and adjust the seasoning.
3. Wash and dry the rocket leaves.
4. Cut the beef into the thinnest slices you can, across the grain. Place them in a single layer with space between each slice on a sheet of non-stick baking parchment. Cover with another sheet of baking parchment and flatten the slices with a rolling pin or mallet until as thin as possible.
5. Arrange the slices of beef, spread out, on each plate. Lay a sheet of baking parchment on top and press down on the beef to make a flat layer.
6. Put the rocket in a bowl and dress with the olive oil, lemon juice and some salt and pepper. Strew the rocket leaves over the beef, shave slices of Parmesan over and drizzle with the horseradish dressing.