Blend mushrooms, onion, shio koji and pepper to a puree
Add tapioca flour and water and mix
Place a layer of cling film onto a baking tray. Pour in a thin later of the mixture, then use a second layer of cling film to create as thin a layer of batter as possible
Steam for 7 minutes
Gently peel off the cling film
Place in a dehydrator and dehydrate until sheet is so brittle it snaps easily (mine took 12 hours at 50'C) Note: The bottom corners of this sheet are too thick, for the perfect cracker it should be transparent at this stage. Thick bits can still be fried, but they aren't as light and crispy.
Break the sheet into pieces (this sheet shows desired transparency)
Deep fry at 170'C until crackers puff and rise to the surface. Drain on a piece of kitchen towel and enjoy!