Place the sushi rice in a colander, rinse throughly and let drain for 15 minutes. Cook rice according to the package instructions or your preference.
While the rice is cooking, mix together the rice vinegar, sugar, and salt, until the sugar and salt dissolves.
Transfer the rice to a large bowl and fluff. Sprinkle on the sushi vinegar and use a rice paddle to fold the sushi vinegar into the rice.
Line a baking tray with parchment paper or plastic wrap. Spread the rice out, pressing it down, until it is about 3/4 inch high. Cover and let cool in the fridge overnight.
The next day, make the spicy tuna and prep the toppings. Cut the tuna into small pieces. Combine the tuna with the kewpie mayo, sriracha, soy sauce, and toasted sesame oil. Keep cold in the fridge.
Take the rice out of the fridge and slice into 2 inch by 3/4 inch pieces. Heat up a generous amount of oil in a pan and heat it up over medium heat.
Add the rice cakes and fry until golden and crispy, flipping once. Drain on a wire rack.
Top the crispy rice with slices of avocado, the spicy tuna, a slice of jalapeño, and a sprinkle of toasted sesame seeds. Enjoy!