Rinse 1 cup of sushi rice under cold water until clear, combine with 1.25 cups water in saucepan, boil, reduce heat, cover, simmer for 15 minutes, and let steam covered for 5 minutes.

Transfer rice to a bowl. Mix 2 tbsp sugar, 3 tbsp rice wine vinegar, 1 tsp sea salt in a small bowl, heat until sugar dissolves, and fold into warm rice.

Line a baking tray with parchment, transfer seasoned rice, press down to create a layer about ¾ inch thick, cover, and refrigerate for 3 hours.

Cut rice into squares, heat ½ inch canola oil in skillet over medium-high heat, and fry squares until golden brown, about 2-3 minutes per side.

Cube 1 cup ahi tuna, mix with 3 tbsp Kewpie mayonnaise, 1-2 tbsp sriracha, 1 tsp soy sauce, and sesame oil if using.

Top each crispy rice square with the spicy tuna mixture and garnish with desired toppings.