Rinse the Sushi Rice under cold water until the water runs clear.
In a saucepan, combine the rinsed rice, kombu, and water. Bring to a boil, then reduce to a simmer and cook until absorbed, about 18-20 minutes. Discard the kombu.
In a small bowl, whisk together rice vinegar, sugar, and salt until dissolved. Fold into warm rice and allow to cool.
Press the cooled rice firmly into an 8x8-inch baking pan. Cover and refrigerate for 1 hour.
Remove chilled rice from the pan and cut into rectangular pieces. Fry each piece until golden brown and crispy, about 3-4 minutes per side.
In a bowl, combine chopped tuna with Kewpie mayonnaise, sriracha, soy sauce, sesame oil, and lime juice. Mix well.
Place a scoop of spicy tuna mixture on each crispy rice bite and garnish with avocado, sesame seeds, furikake, and green onions. Add jalapeño for extra heat.
Notes
For extra flavor, drizzle additional sriracha or spicy mayo on top before serving.