Finely chop the green onion and grate the ginger.

Trim the bottom 1cm of the asparagus, peel the tough lower third, and cut into 1cm pieces.

Microwave the asparagus in a heatproof container covered with plastic wrap for 1 minute at 600W. Rinse under cold water and pat dry. Coat with potato starch.

In a bowl, mix ground chicken, green onion, ginger, sake, and soy sauce until sticky.

Add the prepared asparagus to the chicken mixture, divide into 4 portions, and shape into patties.

Heat salad oil in a frying pan over medium heat. Place the patties in the pan and cook until browned on one side, then flip.

Cook the flipped patties for 2-3 minutes, then cover with a lid and steam over low heat for 5 minutes.

Add the sauce ingredients (sake, mirin, sugar, soy sauce) to the pan and simmer over medium heat until thickened.