Step 1: Preheat your oven to 400°F (200°C). Pat the salmon fillets dry with paper towels. Season lightly with salt and pepper. Place the salmon on a baking sheet lined with parchment paper.
Step 2: Bake the salmon for 12-15 minutes, or until cooked through and easily flakes with a fork. Let it cool slightly, then flake it into small pieces.
Step 3: While the salmon cooks, rinse the sushi rice thoroughly under cold water until the water runs clear. Cook the rice according to package directions (typically 2 ½ cups water for 2 cups rice).
Step 4: In a small saucepan, combine rice vinegar, sugar, and 1 teaspoon salt. Heat gently until the sugar and salt dissolve. Once the rice is cooked, transfer it to a large bowl and immediately pour the seasoning over it. Fold gently with a spatula to combine. Cover the bowl to keep the rice warm.
Step 5: In a medium bowl, combine the flaked salmon, Kewpie mayonnaise, Sriracha, and soy sauce. Mix well until thoroughly combined and creamy.
Step 6: Lightly grease a 9×13 inch baking dish. Spread the seasoned sushi rice evenly across the bottom of the dish, pressing down gently to form a compact layer.
Step 7: Evenly spread the creamy salmon mixture over the rice layer. Sprinkle with 2 tablespoons of furikake and optional toasted sesame seeds. Bake for 15-20 minutes, or until the top is lightly golden and bubbly.
Step 8: Once out of the oven, let the sushi bake rest for a few minutes before slicing into squares. Serve warm with nori sheets, cucumber slices, avocado, and extra Sriracha or soy sauce on the side.