Place the grilled eel in a pan, sprinkle with sake, cover, and steam over medium-low heat for 2 minutes until the liquid evaporates. Let cool and cut into 1.5cm slices.

In a bowl, beat the eggs and mix with sugar, salt, cornstarch, and water. Strain through a sieve.

Heat a pan with salad oil spread thinly using a paper towel. Pour the egg mixture and cook over medium-low heat for 1 minute. Flip and cook for another 30 seconds. Let cool, cut in half, and slice thinly to make shredded egg.

Mix sugar, salt, and vinegar in a bowl. Add the mixture to cooked rice in another bowl. Mix in eel slices, sesame seeds, shredded shiso leaves, and eel sauce (about 1.5 tbsp).