Mince the ginger and cut the cucumber into 4 lengthwise strips.

Cut the egg roll into 7mm thick sticks.

Prepare sushi rice by mixing cooked rice, minced ginger, and sushi vinegar in a bowl.

Make saba soboro by draining and flaking the saba can. Heat sesame oil in a pan, add the flaked saba, and cook until moisture reduces. Add sake, mirin, and doubanjiang, and stir-fry until combined.

Prepare carrot and spinach namul. Julienne the carrot and microwave for 1 minute. Microwave spinach for 1 minute, then rinse and chop. Mix salt, sesame oil, and grated garlic in a bowl, then toss with carrot and spinach.

Lay a sheet of nori on a bamboo mat covered with plastic wrap. Spread half of the sushi rice evenly, then layer saba soboro, cucumber, egg roll, and namul. Roll tightly from the edge. Repeat for the second roll.