Prepare the Spicy Salmon
Finely chop the sushi-grade salmon and place it in a mixing bowl.
In a separate bowl, whisk together the mayonnaise, sriracha, soy sauce, sesame oil, sugar, and green onions.
Pour the sauce over the salmon and gently mix until evenly combined.
Cover and refrigerate until ready to assemble.
Prepare the Rice
Rinse the sushi rice several times until the water runs clear.
Cook the rice according to package directions or in a rice cooker using 3 cups of water.
In a small bowl, combine the salt, sugar, and rice vinegar.
Pour the mixture over the hot cooked rice and gently fold until evenly distributed.
Freeze the Rice
Line a baking sheet or tray with plastic wrap.
Spread the rice into an even layer about 1 inch thick.
Smooth the surface and cover with another layer of plastic wrap.
Freeze for at least 2 hours or overnight for best results.
Fry the Rice
Remove the rice from the freezer.
Cut into rectangles, squares, circles, or desired shapes.
Heat oil in a deep skillet or pot over medium-high heat.
Fry the rice pieces in batches until golden brown and crispy on both sides.
Transfer to a paper towel-lined plate to drain.
Assemble
Place the crispy rice pieces on a serving platter.
Top each piece with a generous spoonful of spicy salmon mixture.
Garnish with toasted sesame seeds and a slice of jalapeño if desired.
Serve immediately while the rice is still crisp.