Make sure the steaks are defrosted before cooking.
Rinse the steaks and pat them dry. Afterwards, sprinkle some salt on the steaks.
Then, put the steaks in your steamer (on a heatproof plate), put the green onions and ginger on top and steam for 15 minutes (or until the fish has become flaky).
To make the sauce, combine mirin, soy sauce, and olive oil in a saucepan and let it boil. Once the fish is done, pour the sauce over it and enjoy!