The key to the perfect crunchy and spicy tuna roll is a balance between spice and crunch. To accomplish this, begin with seasoning the tuna and making up some tenkasu, or crispy tempura flakes. These ingredients are then combined with traditional sushi rice, noni and any other ingredients you may want to create a sushi roll to impress your guests or enjoy on your own.
Make a Batch of Tenkasu
Fill a saucepan with oil and heat to 350 degrees. In a small bowl, combine 1/2 cup of tempura flour, 1/2 cup water and an egg white. Mix with a fork until combined.
Pour the batter slowly into the hot oil, creating drips or lines of batter. One way to do this is to pour the batter over the tines of a fork. Let the batter cook, stirring occasionally, for 2 minutes or until golden brown.
Remove the batter with a slotted spoon and place on a plate with a paper towel to allow excess oil to drain. Break up the crispy batter into little pieces with the back of a spoon. Let the tenkasu cool until you are ready to assemble the sushi rolls.
Seasoning the Tuna
Cut the raw tuna into small cubes and set aside. When purchasing tuna, talk with the butcher to make sure you have sashimi-grade tuna.
Combine 1/4 cup Kewpie Japanese mayonnaise with Sriracha sauce. Sriracha sauce is spicy, so begin with a small amount and add more depending on how spicy you want your rolls. Season the sauce with salt and pepper, chopped scallions and sesame seeds, if desired.
Add the chopped tuna to the sauce and stir until it is coated. Set aside.
Assembling the Roll
Set up your sushi area with the rice, noni, tenkasu, tuna and any other ingredients you may want to include. Ensure each component is easily accessible. Lay out the bamboo sushi mat and place a small bowl of warm water beside it.
Place a half sheet of noni on the bamboo mat. Moisten your fingertips in the warm water and collect enough rice to form a small ball in your palm. Place the ball of rice in the center of the noni sheet and, using your fingertips, press and spread the rice to cover the entire sheet.
Place a line of the tuna across the center of your rice, lengthwise. Sprinkle the tenkasu along the line of tuna. Add any additional ingredients, such as avocado, along this line.
Lift the bottom edge of the mat and begin rolling toward the top, until the bottom edge touches the center and forms a cylinder. You may need to use your fingers to gently push the edge of the roll under to create a fluid roll. Lift up the edge of the mat and continue rolling, applying slight pressure to ensure a tight roll. Once the task is complete, gently squeeze the mat around the roll.