In a bowl, season cooked rice with soy sauce, rice vinegar, and sesame oil. Press firmly into a parchment-lined baking dish and chill for at least 30 minutes.
Cut chilled rice into small squares or rectangles.
Heat vegetable oil in a skillet over medium heat. Fry rice pieces for 2–3 minutes per side until golden and crispy. Drain on paper towels.
In another bowl, mix salmon, mayonnaise, and sriracha.
Top each crispy rice square with a scoop of salmon mixture. Garnish with sesame seeds, green onions, and a drizzle of sriracha if desired.
Notes
For a spicier kick, mix a little extra sriracha into the salmon topping or add diced jalapeños.