• Before You Start: Gather all the ingredients. For the steamed rice, please note that 1½ cups (300 g, 2 rice cooker cups) of uncooked Japanese short-grain rice yield 4⅓ cups (660 g) of cooked rice, enough for 2 donburi servings (3⅓ cups, 500 g). See how to cook short-grain rice with a rice cooker, pot over the stove, Instant Pot, or donabe.
  
• To make the sauce, combine the sauce ingredients in a small saucepan and bring to a boil. Remove from heat and transfer the sauce into a small bowl, set on ice over a larger bowl.
  
• Slice the albacore tuna into about ½ inch (1.3 cm) thick slices and marinate in the sauce for 10 minutes.
  
• Cut the scallion into fine slices. Roll up the shiso leaves together and slice thinly.
  

To Serve

• Put steamed rice in bowls and let cool a little. Sprinkle the shredded nori and sesame seeds. Place the marinated albacore tuna on top.
  
• Grate the ginger. Garnish the sashimi with scallion, shiso leaves, ginger, and wasabi on top.
  

To Store

• You can keep the leftovers in an airtight container and store in the refrigerator for a day.