Combine the water, mushroom and kombu and stand in the fridge for 12 hours. After 12 hours strain the liquid and reserve the mushrooms to fry and use as a garnish.
Knead flour, vinegar and water to a firm smooth dough, wrap and rest for at least 3 hours in the fridge
For the dumpling filling blend the ingredients to a smooth paste
When ready roll the dough out to 2mm thickness and prepare the dumplings
Warm the broth, cook the dumplings, separately, in boiling salted water.