Take the beef tenderloin and, with a sharp knife, cut it into small or fine cubes, depending on your taste. Place the chopped meat in a large bowl and add the finely chopped capers and parsley. A pinch of salt, pepper and a drizzle of extra virgin olive oil will complete your mixture. Mix all the ingredients well with a spoon or spatula, making sure you get a smooth amalgam. Cover the bowl with plastic wrap and let it rest in the refrigerator for at least 15 minutes. This will allow the flavors to blend and the meat to flavor properly.

For the mustard sauce

In a small bowl, pour the mustard and add the Balsamic Vinegar. A drizzle of extra virgin olive oil, a pinch of salt and pepper, and carefully mix all the ingredients with a spoon or hand whisk, creating a smooth, even sauce. 

Use a pastry cup to shape the beef tartare into a medallion, then arrange it on a serving plate. Garnish it with fresh arugula and slivers of Parmigiano Reggiano. Finally, dress the medallion with the Balsamic Vinegar mustard sauce.