Boil rice in water for 15 minutes, then simmer on low for 4 minutes until tender.
Mix salmon, mayonnaise, mirin, sriracha, and coriander stems in a bowl.
Spread warm rice on a tray and sprinkle with a mixture of rice vinegar and sugar.
Stuff 2 tablespoons of rice with 1 tablespoon of salmon mixture and roll into balls.
Coat balls in beaten egg and roll in a mixture of panko breadcrumbs and sesame seeds.
Deep fry balls in oil at 190°C for 3 minutes until golden-brown.
Combine mayonnaise, oyster sauce, and sriracha paste for the dipping sauce.
Serve rice balls hot garnished with coriander and amaranth.