Mince the onion and microwave it for 1 minute at 600W. Let it cool. Remove the pits from the pickled plums and mash them into a paste.

Wrap the tofu in kitchen paper and microwave for 1.5 minutes at 600W to remove excess water. Let it cool.

Finely chop the horse mackerel fillets and mash them until sticky.

In a bowl, combine mashed horse mackerel, crumbled tofu, onion, seasonings (☆), and half of the mashed plum paste. Mix well and divide into two portions.

Heat salad oil in a pan over medium heat. Shape the mixture into patties and cook until browned. Flip, cover, and steam on low heat for 3-4 minutes. Remove from the pan.

Wipe the pan clean and add the remaining plum paste and sauce ingredients (★). Stir and bring to a boil to create the plum sauce.