Rinse sushi rice under cold water until it runs mostly clear. Combine with water in a medium pot, cover, and bring to boil over medium heat. Reduce the heat to low and simmer for 15 minutes until water is absorbed.

In a small saucepan, mix rice vinegar, sugar, and salt. Heat until sugar dissolves. Mix into cooked rice in a large bowl, press into baking dish, and chill for at least 30 minutes.

Cut chilled rice into 2-inch pieces using a sharp knife.

Heat vegetable oil to 350°F (180°C) in a frying pan. Fry rice pieces in batches for 1-2 minutes on each side until golden brown. Transfer to paper towels to drain.

Combine Kewpie mayonnaise, sriracha, soy sauce, and lime juice in a mixing bowl.

Chop ahi tuna into small cubes and mix with the spicy mayo. Slice avocado and jalapeños.

Assemble by placing avocado on each rice piece, adding spicy tuna mix, and topping with jalapeño slices and sesame seeds.