Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper. Place the salmon fillet on the sheet, drizzle with olive oil, and season with salt and pepper. Bake for 12-15 minutes, until cooked through and easily flaked. Set aside to cool slightly.

While the salmon bakes, rinse the sushi rice under cold water until the water runs clear. Cook the rice with water according to package directions or in a rice cooker. In a small bowl, whisk together the rice vinegar, sugar, and 1 tsp of salt until dissolved (you can warm it for 15 seconds in the microwave to help). Once the rice is cooked, transfer it to a large non-metallic bowl, pour the vinegar mixture over it, and gently fold to combine. Let it cool slightly.

Once the salmon is cool enough to handle, use two forks to flake it into bite-sized pieces in a medium bowl. Add the Kewpie mayonnaise, sriracha, soy sauce, and optional masago/tobiko. Gently mix until the salmon is evenly coated. Taste and adjust seasoning if needed.

Press the seasoned sushi rice into an even layer in an 8x8 inch baking dish. Sprinkle a generous, even layer of furikake over the rice. Carefully spread the creamy salmon mixture over the top, reaching the edges. Sprinkle the remaining furikake over the salmon.

Bake in the preheated 400°F (200°C) oven for 10-12 minutes, until heated through and lightly golden on top. For a browner top, you can broil for 1-2 minutes, watching carefully to prevent burning. Let it rest for a few minutes before serving.

Serve warm, scooping portions onto roasted seaweed snacks. Garnish with sliced avocado, cucumber, and scallions.