Heat the oil in a large frying pan or wok.
Sauté the beef, onion, sesame seeds, garlic, and mushrooms until the meat is uniformly changed colour.
Stir in all the remaining ingredients and stir-fry for a further minute or two.
Transfer to a bowl, mix thoroughly, cover and leave to cool.
To make the dumplings, use one of the pasta doughs on pages 87-90 and break off 2.5-cm dough balls.
On a floured board, roll the balls into 7.5-cm discs.
Place 1 tablespoon of the mixture on the lower half of the circle, paint the edge with an egg wash or egg-yolk, and fold over to make a moon-shaped patty.
Crimp and press the edges to seal.
Poach for 3–4 minutes in simmering broth.