Method
Preparation
Combine the cooked sushi rice with rice vinegar, sugar, and salt in a bowl. Mix gently until well coated and allow to cool slightly.
Spread the rice into a flat layer in a lined baking dish, about 1 inch thick. Press down firmly and refrigerate for at least 30 minutes.
Cut the chilled rice into squares or rectangles for uniform frying.
Frying
Heat vegetable oil in a large skillet over medium-high heat until about 1/2 inch deep and shimmering.
Dust each rice square lightly with flour. Fry until golden brown and crispy on both sides, about 2-3 minutes per side.
Topping
Mix the diced tuna, mayonnaise, sriracha, soy sauce, and sesame oil in a bowl until well combined.
Spoon a generous amount of the spicy tuna mixture onto each crispy rice square.
Garnish with sliced green onions and sesame seeds.
Serve immediately while still crispy.
Notes
Serve with additional sriracha for those who like an extra kick. Enjoy fresh for the best texture.