Chop the beef into thin slices lengthwise, and then crosswise into small cubes.
In a bowl, combine the other ingredients for the flavoring sauce (worsterchire sauce, mustard, parsley, salt, pepper, chives, capers, etc.)
Mix the beef, flavoring sauce, and optional shallots together.
Place a cookie cutter about 7.5 cm (3 in) in diameter on a plate and fill with tartare. (Alternatively, you can serve it in a glass.)
Press the tartare with the back of a spoon to even the surface.
Unmold gently. Repeat to form the other portions.
Put in the fridge for 10 minutes.
Gently crack open the egg, and add the egg yolk into each portion.
Serve when ready.