Preheat oven to 200°C top and bottom heat.
Brush the saddle of veal with Dijon mustard and season with salt and pepper. Heat some oil in a pan (fireproof incl. handle!), sear the meat briefly and then put it in the oven. After about 8 minutes, turn it over and finish frying. The meat should be tender pink. Duration: depending on the thickness of the meat about 20 minutes.
When the meat is done roasting, remove from the pan to prevent dragging and refrigerate.
For the truffle dressing, put the sour cream in a bowl, season with salt, pepper and truffle oil.
For the balsamic sauce, briefly boil the vinegar with the same amount of granulated sugar over low heat to reduce slightly. Allow to cool.
Cut mozzarella into cubes of about 1 cm. Marinate with olive oil, salt, pepper and a little truffle oil.
Wash tomatoes, cut into quarters, wash lettuce, pluck stems and marinate like the mozzarella.
Then cut the veal into thin slices with a slicer. Place on plates, top with the mozzarella, lightly spread tomatoes and lettuce on top. Drizzle with a little truffle dressing and serve with fresh truffles.