The quintessential Polish ceremonial starter: prime hand-chopped raw beef tenderloin formed into neat rounds, served with an unbroken egg yolk, pickled cucumbers, marinated mushrooms, and sharp onions.
Chill the beef tenderloin in the freezer for 15 minutes to firm it up. Using a very sharp chef's knife, slice the beef into razor-thin sheets, then matchsticks, and finely dice by hand (avoid electric grinding to preserve velvety mouthfeel).
In a chilled bowl, mix the beef with the oil, cold sparkling water, salt, black pepper, and a dash of Maggi. Knead lightly with a fork until the meat becomes supple, glossy, and holds its shape.
Divide the beef into two equal portions. Using a round metal ring mould, press the meat onto chilled ceramic plates into smooth circular pucks. Indent a small crater in the centre with the back of a soup spoon.
Carefully nestle an unbroken raw egg yolk into each crater. Surround the meat puck with neat mounds of minced onion, pickled cucumbers, and marinated mushrooms, serving with crusty sourdough bread.