Rinse uncooked sushi rice under cold water until water runs clear. Cook with water in a saucepan, bring to boil, then simmer covered for about 15 minutes. Let cool.

Combine rice vinegar and white sugar in a microwave-safe bowl. Microwave for about 30 seconds until sugar dissolves, then fold into cooled sushi rice.

Preheat oven to 400°F (204°C). Spray muffin tin with cooking spray.

In a bowl, mix cubed salmon, soy sauce, Kewpie mayo, sriracha, and sesame oil. Stir until evenly coated.

Cut nori sheets into squares big enough for muffin tin, about 4 inches.

Press sushi rice into each nori square, then spoon salmon mixture into each cup.

Bake in oven for about 15 minutes until golden brown and crisped.

Allow to cool slightly, then garnish with sriracha, Kewpie mayo, furikake, and green onions before serving.