Tuna-mayo onigiri with soy flavored rice
Mix tuna, mayo, and a couple of pinches of salt in a bowl. Season rice with Mentsuyu.
Wet hands with water. Take about 3/4 cup rice in one hand, press and form into a round shape. Make a well in the middle of the rice ball and put in tuna mixture. Close the well with 1/4 cup rice. Reshape and wrap with a sheet of roasted seaweed if you want. Repeat to make three more Onigiri.