Begin by mincing the imitation crab and green onions finely. In a medium bowl, mix together the minced crab, Japanese mayo, Sriracha, and green onions until well combined. Refrigerate the filling for about 15 minutes.

Wet your hands with salt water. Take a handful of warm rice, shape it into a flat disc, create a well in the center, fill with crab mixture, and cover with more rice to form a triangle.

If using a mold, fill the bottom half with rice, press down to create a well, add filling, cover with rice, and compact. Release onto your palm and continue until all filling is used.

Wrap the finished onigiri with a strip of nori and sprinkle with furikake. Arrange on a plate and serve immediately.