Start by rinsing the sushi rice thoroughly, then cook it in a pot or rice cooker according to the package instructions. Once it's cooked, mix in the rice wine vinegar and a pinch of salt. Allow the rice to cool to a slightly warm or room temperature.

Shred the imitation crab by pulling each stick apart with your hands, similar to string cheese. Combine it with sriracha, kewpie mayo, and another pinch of salt, mixing until everything is well blended.

On a cutting board, lightly brush with a thin layer of oil. Rehydrate one square sheet of rice paper in warm water, then place it on the cutting board. Rehydrate a second sheet and layer it on top of the first.

Place a sheet of nori on top of the rice paper. Using scissors, make a single slit from the center of the bottom edge of the square to the middle.

Spread about 2-3 tablespoons of the imitation crab mixture on the bottom left section of the rice paper and nori. Add the thinly sliced cucumber and avocado to the top left section.

Spread an even ½-inch layer of rice over the top and bottom right sections, being careful not to overstuff, as this will make folding difficult.

To fold the sushi sandwich, start with the bottom left section and fold it upwards. Then fold the pouch to the right, and finally fold it down to create a compact sushi sandwich.

Heat a generous amount of neutral oil in a pan over medium heat. Add the sushi sandwiches and fry on medium-high heat for 3-4 minutes on one side until they are crispy. Flip and fry the other side for another 3-4 minutes.

Serve the sushi sandwiches warm and crispy, accompanied by spicy mayo sauce on the side.