Begin by preparing the sushi rice according to its package instructions, typically rinsing it well and cooking it in a rice cooker or on the stove. In a small bowl, mix rice vinegar with white sugar and microwave until dissolved. Once the rice is ready and still warm, gently fold in the vinegar mixture, ensuring an even distribution, and allow it to cool while you prepare the other components.

In a medium-sized mixing bowl, cube the fresh salmon into bite-sized pieces. Add light soy sauce, Kewpie mayo, sriracha, and sesame oil, carefully blending the ingredients until the salmon is well-coated and the mixture is creamy with a hint of spice. Set this flavorful salmon mixture aside while you prepare the nori cups.

Take your nori sheets and carefully cut them into squares that will fit snugly into the cups of a muffin tin. The nori should have enough overlap to hold the filling but not be too large. This step is essential for ensuring your Baked Salmon Sushi Cups maintain their shape while baking.

Lightly grease the muffin tins with cooking spray to prevent sticking. Press a piece of nori into each cup, forming a natural bowl shape. Spoon a generous amount of the prepared sushi rice into the nori, packing it down firmly. Finally, top each rice-filled nori cup with an equal portion of the salmon mixture, ensuring they are filled to the brim for a hearty bite.

Preheat your oven to 400°F (200°C). Place the muffin tin in the oven and bake the sushi cups for about 15 minutes, or until the salmon appears cooked through and the tops are a golden brown. Keep an eye on them to prevent over-baking, which can lead to dryness.

After baking, remove the sushi cups from the oven and let them cool for a moment. Drizzle additional sriracha or spicy mayo on top if desired. Sprinkle with furikake and garnish with chopped green onions for that extra crunch and flavor. Serve your warm Baked Salmon Sushi Cups immediately, and savor the delightful fusion of tastes!