 A list and photos of the most common traditional fillings are on the Onigiri on Parade page. The top three traditional fillings are: umeboshi (pickled plums), shake (salted salmon - how to make your own from fresh salmon) and okaka (katsuobushi or bonito flakes flavored with soy sauce).  A list and photos of the most common traditional fillings are on the Onigiri on Parade page. The top three traditional fillings are: umeboshi (pickled plums), shake (salted salmon - how to make your own from fresh salmon) and okaka (katsuobushi or bonito flakes flavored with soy sauce). 