Preheat your oven to 350°F / 175°C and lightly grease a baking sheet.
In a small bowl, toss the eggplant pieces with dark sesame oil and soy sauce.
Spread them on the prepared baking sheet and roast for 8–10 minutes.
Let cool completely before using.
To assemble, place a nori sheet on your cutting board or bamboo mat, rough side up, with the long edge parallel to you.
Lightly wet your fingertips in cool water and spread about ¾ cup / 150 g (5.3 oz) of sushi rice evenly over the entire surface of the nori.
Carefully flip the nori over so the rice is face down on the cutting board.
Arrange ¼ of the cooled eggplant pieces and ¼ of the shiitake slices in a line across the center of the nori.
Using your fingertips to hold the filling in place, lift the edge of the nori closest to you with your thumbs.
Roll it over the filling, tucking it in tightly to create a firm cylinder.
Continue rolling until the roll is complete.
Gently shape the roll using a bamboo mat (covered in plastic wrap for easy cleanup), pressing firmly to create a compact roll.
Repeat with the remaining to create 3 more rolls.
Drape the roasted red pepper strips across the top of each completed roll.
Cover with a sheet of plastic wrap.
Dip the tip of a very sharp knife in water.
Cut each roll into 8 even pieces, wiping the knife clean between cuts.
Use the bamboo mat one last time to gently press the red pepper strips into the top of each piece.
Remove the plastic wrap.
Arrange the sushi on a serving platter and garnish with thinly sliced green onion.
Keep a small bowl of water nearby to dip your fingers in. This prevents the sticky sushi rice from clinging to your hands while you spread it on the nori.
