Put rice in non-stick pot or rice cooker with 4 cups water and kombu. let boil for 5 minutes. Turn down heat to very low and cook till all water is absorbed (appx 15 mintues). Then turn off heat and keep covered for another 15 mintues.
When rice is almost finished in the above, mix vinegar, sugar, and salt in small saucepan and heat. Stir till all sugare is dissolved. Then quickly cook the mixture by placing in a small metal bowl that sits in a cold water bath.
Spread rice out in large baking pan (or similar large container). Using a flat paddle, toss the rice (carefully so as not to break noodles). Fan the rice to cool it quickly and sprinkle on the vinegar mixture as you do this (having two people to do this helps).
Rice should end up slightly sticky whole grains with a glossy sheen and very slight sweet-sour taste.
Mix water and salt in small pot and bring to boil. Add kampyo and boil for a couple minutes. Then rinse and drain the kampyo.
Bring dashi, soy sauce, and sugar to a boil. Add softened kampyo and cook for half an hour till most of the liquid is absorbed. Drain and cool kampyo and use as nori maki filling
Remove stems and slice caps into 1/8 inch slices. Rinse caps to make sure there is no dirt clinging to them.
Bring remaining ingredients to boil and add mushrooms. Lower to simmer and cook for 15-20 minutes or until all liquid is absorbed.
Use as nori maki filling.
Servings: