For the bread dumplings, place the bread cubes in a large bowl. Whisk milk with eggs, porcini salt, parsley and dried porcini mushrooms and stir in flour.
Cut onion into cubes, fry in a little oil and add the milk mixture. Pour over the bread cubes and then let sit for at least half an hour.
Mix with your hands and form 8 to 10 dumplings. In a large pot, bring water with salt to a boil, put in dumplings, turn down and let simmer (not boil) for 20 minutes.