Toast the nori seaweed sheets by passing them quickly over an open flame of your gas stove or toasting them in a dry skillet over medium heat until they become crisp and fragrant, about 1-2 minutes per side. Be careful not to burn them. Let them cool.
Once cooled, crumble the nori seaweed sheets into small pieces. You can use scissors or tear them by hand.
Toast the sesame seeds in a dry skillet over a medium heat for about 2 minutes or until lightly toasted. Transfer to a bowl and allow to cool.
In a small mixing bowl, combine the crumbled nori seaweed with the toasted sesame seeds, (and bonito flakes and shiso, if using).
Stir well until all the ingredients are evenly distributed.
Transfer to an airtight container or a small jar for storage.
Store in a cool, dry place away from direct sunlight. It will keep for several weeks.
Sprinkle the furikake over rice, noodles, salads, vegetables, or any other dish you'd like to add flavor to.