Add short-grain rice to the rice cooker with water as per your cooker’s instructions, in a 1:1 ratio. Once cooked, remove from heat and add sushi vinegar.
Cut salmon fillets into ½-inch slices
In a small bowl, add the sriracha sauce and mayonnaise. Stir until pink-orange in color and well combined.
Add salmon slices to sriracha-mayo sauce and combine well
Place bamboo mat flat out on a counter surface and add a single layer of plastic wrap on top
Place one nori sheet on the bamboo and gently spread rice on the sheet, creating an even layer of rice out to the sheet’s edges. Cover any big gaps with more rice and sprinkle on black sesame seeds.
Carefully turn the nori sheet over so that the rice is facing down on the bamboo mat. Arrange salmon and avocado slices towards the edge of the sheet nearest you.
Gently lift up the mat edge nearest you and carefully roll the mat away from you, wrapping the nori and rice. Ensure that you don’t roll the mat into the sushi. Remove the mat and plastic wrap.
Garnish with extra spicy mayo and green onion. Slice the sushi to serve.