In a medium-sized bowl, combine salmon, Japanese mayo, soy sauce, rice vinegar, & sriracha (if using). Set aside.
In the onigiri mold, sprinkle a very small amount of salt, add enough rice to cover the bottom of the mold. Then, add about 1 ½ tablespoon of salmon filling in the center, then more rice on top to cover the filling.
Put the top of the mold on top, then gently & firmly press to make rice tightly packed. You should feel a little resistance, but if you don’t, you might want to add a bit more rice so your onigiri is full & tightly pressed together. Press the back of the mold to release the onigiri.
Wrap onigiri with a piece of nori.
Roll the sides of the onigiri in furikake, if using. Repeat for remaining filling & rice. Enjoy immediately!
