Step 1: Rinse the sushi rice under cold running water in a fine-mesh strainer, gently agitating the grains with your fingers. Continue rinsing until the water runs completely clear, which removes excess starch and prevents gummy rice.

Step 2: Cook the rinsed rice with 2 ¼ cups water in your rice cooker following the manufacturer’s instructions, or use the stovetop method by bringing to a boil, then reducing to low heat, covering, and simmering for 18-20 minutes.

Step 3: While the rice cooks, prepare your seasoning mixture. Combine rice vinegar, sugar, and salt in a microwave-safe bowl. Microwave for 30 seconds, stirring until the sugar and salt dissolve completely into the vinegar.

Step 4: Transfer the hot cooked rice to a large mixing bowl. Gently fold in the vinegar mixture using a cutting and folding motion with a rice paddle or spatula. Avoid stirring vigorously, which can break the grains and create mushy rice.

Step 5: Line a sheet tray or baking dish with plastic wrap, leaving excess hanging over the edges. Press the seasoned rice firmly into an even layer about ½-inch thick. The more compact you press it, the better it will hold together when frying.

Step 6: Cover the top with another layer of plastic wrap and press down with a flat object like another tray or a cutting board. Refrigerate for at least 2 hours, though overnight chilling produces the best results for firm, fry-able rice cakes.

Step 7: Using a sharp knife, finely mince the sushi-grade tuna into small pieces with a consistency similar to a coarse paste. Avoid over-processing, as some texture is desirable.

Step 8: In a medium bowl, combine the minced tuna with Japanese mayo, Sriracha sauce, soy sauce, sesame oil, and thinly sliced scallion. Mix thoroughly until all ingredients are evenly distributed.

Step 9: Taste the mixture and adjust the seasoning-add more Sriracha for heat, mayo for creaminess, or soy sauce for saltiness. Cover and refrigerate until assembly time.

Step 10: Remove your chilled rice block from the refrigerator and peel away the plastic wrap. Using a sharp knife dipped in water (to prevent sticking), cut the rice into bite-sized rectangles or squares, approximately 2×1 inches.

Step 11: Heat about ½ inch of neutral oil in a non-stick skillet or heavy-bottomed pot over medium-high heat. Test the oil temperature by dropping in a small piece of rice-it should sizzle immediately.

Step 12: Carefully place rice pieces in the hot oil, working in batches to avoid crowding. Fry each side for 2-3 minutes until golden brown and crispy. The edges should be deeply golden and crunchy.

Step 13: Remove the crispy rice cakes with a slotted spatula and transfer to a wire rack or paper towel-lined plate. Immediately sprinkle with a pinch of salt while still hot.

Step 14: Top each warm crispy rice cake with a generous dollop of the spicy tuna mixture. Add your choice of garnishes-avocado slices, jalapeños, a drizzle of eel sauce, or black sesame seeds. Serve immediately while the rice is still warm and crispy.