To use Dried mushroom is essential for a Vegetarian Japanese cooking. I don’t know about your situation but where I live is difficult to get good quality ones… Often so expensive or can’t find organic ones and treated with pesticide etc.. So I decided to make my own ones.
Wipe them off with a dump cloth and keep under the sun in airy condition for up to 5days…. If they are too big then you can slice them too.. Make sure to remove damaged or dirt parts. Once you dried them, put them in a sterilized air tight jar and keep in a cold dark place.