01 - Rinse sushi rice under cold water until the water runs clear. Combine rice and water in a rice cooker or medium saucepan; cook according to package instructions. While rice is still warm, gently fold in rice vinegar, sugar, and salt until evenly distributed. Allow the rice to cool to room temperature.
02 - Simmer shiitake mushrooms in soy sauce and mirin with a splash of water for 10 minutes until tender and infused with flavor. Allow mushrooms to cool, then slice thinly.
03 - Whisk eggs with sugar and soy sauce. Heat a nonstick skillet over medium-low heat, pour in egg mixture, and cook gently to form a thin omelet. Let the omelet cool, then slice into long strips.
04 - Soak dried kampyo in water for 30 minutes. Drain well, then simmer in soy sauce, sugar, and mirin until tender and seasoned. Allow to cool before using.
05 - Julienne cucumber, carrot, and pickled daikon. Slice avocado into even strips.
06 - Place a sheet of nori, shiny side down, on a bamboo sushi mat. With wet hands, spread an even layer of prepared sushi rice over two-thirds of the nori, leaving the top third empty.
07 - Lay omelet strips, cucumber, carrot, shiitake, kampyo, pickled daikon, and avocado in a horizontal line across the rice.
08 - Using the sushi mat, roll the nori tightly into a cylinder, applying gentle pressure. Seal the edge with a little water so the roll stays closed.
09 - Let the sushi roll rest for a few minutes to firm up. Slice into thick rounds using a sharp, damp knife. Serve with soy sauce, pickled ginger, and wasabi if desired.