Cook your rice in a rice cooker with the water, kombu and pinch of salt.
Mix the sugar and rice vinegar well. Add it to the rice along with the potato starch and mix really well.
Cover a container with plastic wrap and press the rice really well. You want it like ¼-½ inch thick depending on preference. Cover with the plastic wrap, place another container over it with some cans for weight. Refrigerate for 4-8 hrs and then place in the freezer for 30 min.
Add the mirin, tamari and sugar to a sauce pan and boil. Simmer for 5-7 min or until it coats the back of a spoon. Let cool.
Chop your tuna really finely, almost like a paste. Add the japanese mayo, sriracha, chives, sesame oil, tamari and sugar. Mix.
Cut your rice into rounds or squares. This yields between 12-16 depending on the size of your rounds. Mine was 2 in.
Cover your pan with about ½ inch of oil. Add your rice and fry until golden on both sides. Should be about 8-10 min.
Pipe your tuna onto the rice, top with more chives, avocado, serrano and eel sauce.
