Cook the sushi rice according to package instructions, typically around 18-20 minutes. Combine rice vinegar and sugar in a bowl, stir until dissolved, and fold into warm rice.

Preheat your oven to 400°F (200°C) to achieve a golden finish on the sushi cups.

Combine fresh salmon, soy sauce, kewpie mayo, sriracha, and sesame oil in a bowl. Mix gently until evenly coated.

Cut nori sheets into squares large enough to form a cup shape in the muffin tin. Set aside.

Grease muffin tin with cooking spray. Press sushi rice into the center of each nori square and top with salmon mixture.

Bake assembled sushi cups in the preheated oven for approximately 15 minutes until salmon is cooked and nori is crispy.

Let cool briefly, then drizzle with more sriracha, sprinkle with furikake and green onions before serving.