Cook sushi rice according to package instructions, rinsing until clear, then cooking for about 20 minutes. Mix in rice vinegar and sugar, allowing it to cool.

In a bowl, combine cubed sushi-grade salmon with light soy sauce, Kewpie mayo, sriracha, and sesame oil. Fold gently until coated.

Preheat the oven to 400°F (200°C) for even cooking and to crisp the nori.

Grease a muffin tin with cooking spray. Cut nori sheets into squares and line each muffin cup. Add sushi rice and press down, then top with salmon mixture.

Bake in the preheated oven for about 15 minutes until salmon is cooked through and nori is crispy.

Remove from oven, cool slightly, and garnish with sriracha, Kewpie mayo, furikake, and green onions. Serve warm.