Dab the fillet dry. If necessary, carefully remove all skins and tendons all around with a sharp knife. In the original recipe, the fillet is then put in a cool place (approx. 5 hours) so that it is well chilled before being cut.
You can also freeze it for about 1 hour to make it easier to cut afterwards.
For the mayonnaise, mix mustard, vinegar and egg yolk with the whisks of the mixer. Stir 200 ml oil first in droplets, then in a fine jet. Season to taste with Worcester sauce, lemon juice, salt and pepper.
Cut the chilled meat into very thin slices with a very sharp knife across the fibre, as evenly as possible and without much back and forth movement.
Spread two large pieces of cling film thinly with oil. Place a few slices of meat between each of them with a space in between. Carefully roll out even thinner with a pastry roll. Make sure that the meat does not tear so that you can arrange it without it falling apart.