Mackerel stewed in miso broth is an alternative to simple salted and grilled fish.
1 whole mackerel, seperated into fillets
5 green onion, cut into 3 inch lengths
1 small piece of ginger, peeled and julienned
1/2 cup mirin
1/2 cup sake
4 1 inch squares of kombu, softened in water. Keep the water.
3 tbsps akamiso
5 tsp shiro miso
Blanch the green onions then remove and place into ice water. Drain, then set aside. Then, boil each fillet of fish in the same water in which the onions were blanched, until surface of the flesh is skin turns white. remove and dunk into ice water, then drain.
In a large skillet enough to fit all of the fish, layer the ginger on the bottom, then the fish skin side down. Add the mirin, sake, and the water in which the kombu was soaked in. Boil and skim the foam, then reduce and simmer for about 12 minutes, covered.
Dilute the miso with the liquide in the skillet, then add to the skillet. Cook for another 3 minutes, then add the green onion and turn off the heat. Let it rest.
After 5 minutes, serve with the sauce. If the sauce isn’t thick enough, simply boil the sauce only until it thickens.