Prepare the meat and let it cool down well. Soak porcini mushrooms in approx. 80 ml hot water for approx. 30 minutes.
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.
Chop the Parmesan cheese into fine shavings with a peeler. Clean the mushrooms, wash if necessary and cut into very thin slices. Wash the chives, shake dry and cut into small rolls.
For the jam, peel and finely dice the shallots. Heat 1 tbsp. oil, fry the shallots for approx. 3 minutes until translucent. Pour porcini mushrooms into a sieve, collecting soaking liquid. Squeeze the mushrooms and chop them finely.
Add the mushrooms and sugar to the shallots, caramelise briefly. Deglaze with balsamic vinegar and 4 tablespoons soaking water. Bring to the boil and simmer for about 3 minutes until thick. Season to taste with a little salt and pepper.
Take the meat out of the fridge, cut into very thin slices and roll out. Arrange meat on plates. Season with a little salt and pepper. Spread mushrooms, chives and parmesan on top.
Sprinkle with the shallots jam. Mix the mayonnaise with approx. 3 tbsp. of mushroom soaking water to make a thick sauce. Spoon in strips over the carpaccio. Add the rest of the mayonnaise.