Whisk the egg, milk and salt together, then knead with enough flour to form an elastic, not too firm dough. Shape it into a ball and let it rest under a bowl for at least 30 minutes.
For the filling:
Knead all ingredients together.
Roll out the pasta dough and cut out small circles. Place 1/2 teaspoon of minced meat filling on each, fold up in a crescent shape and close the edges thoroughly; place the ends of the crescent moon on top of each other and press together. Place on a well-floured board (otherwise it will stick and tear).
Bring 2 liters of salted water with peppercorns and the bay leaf (possibly also a whole peeled onion) to the boil, then cook the dumplings in portions for 15 minutes in gently boiling water.
Before serving, toss in butter to taste and serve with sour cream. Or put a ladle of the broth in which the pelmeni were cooked in a soup plate, season with 1 teaspoon of vinegar and add a few pelmeni; then they are eaten like dumplings.