Rinse the sushi rice in cold water 3-4 times until the water is mostly clear.
Cook the rice according to the package instructions. Remove from heat and let it cool slightly.
Add sushi vinegar to the rice and cut it in with a wooden spoon (don’t stir or the rice will break down and become soggy.)
Meanwhile, season the salmon with salt and pepper. Cook over low heat to an internal temperature of 125°F. Set aside for the salmon to cool. Once cooled, break it up into smaller pieces with a fork or your hands. Refrigerate until ready to assemble.
Press 2 large tablespoons of rice into each cup of a muffin tin until compacted. Chill in the fridge for about 20 minutes so the rice sets.
In a bowl, whisk together mayo, Sriracha, and soy sauce.
When ready to assemble, get the rice from the fridge. Pull the rice cups out of the muffin tin and place them on a serving platter. Fill with each of the components. Top with Sriracha mayo and furikake.