Cook and season the rice. Prepare sushi rice according to package instructions. While it’s still warm, mix in rice vinegar, sugar, and salt. Stir gently so you don’t mash the grains. Let it cool until just warm.

Press the rice. Line a small baking sheet or 8x8 pan with plastic wrap. Lightly wet your hands and press the rice into an even 3/4-inch layer. Cover and chill for at least 1 hour, or up to 24 hours. This helps the cakes hold their shape.

Make the spicy tuna. In a bowl, combine mayo, sriracha, soy sauce, rice vinegar, and sesame oil. Fold in the diced tuna and green onion. Adjust heat with more sriracha if needed. Cover and refrigerate until ready to assemble.

Cut the rice cakes. Lift the chilled rice slab out of the pan. Using a sharp, wet knife, cut into bite-size rectangles or squares, about 1.5 by 2 inches. You should get 12–16 pieces.

Preheat the air fryer. Set to 400°F (200°C) for 3–5 minutes. Lightly spray the basket with neutral oil.

Crisp the rice. Spray the tops and bottoms of the rice pieces with oil. Arrange them in a single layer in the air fryer basket, leaving space between pieces. Air fry for 8–12 minutes, flipping halfway, until golden and crisp on the outside. Work in batches if needed.

Season the crisps. While hot, sprinkle a pinch of salt on the rice cakes. This wakes up the flavor.

Assemble. Spoon a heaping teaspoon of spicy tuna onto each rice cake. Add a jalapeño slice, sesame seeds, and chives. If you like, tuck on a sliver of avocado and a tiny strip of nori.

Serve right away. Crispy rice is best within minutes of assembly while the base is hot and the topping is cool.