Cut the mackerel into 3 pieces and sprinkle salt on both sides. Let it sit for 10 minutes. The salt will remove moisture from the fish, which helps reduce the fish smell.
Put the mackerel in a strainer and pour boiling water over it to remove the fish smell. This one extra step will make the mackerel really delicious.
To infuse the mackerel with a sweet flavor, add the water, sugar, sake, ginger, and umeboshi to a pot and bring to a simmer. Turn off the heat for a moment, arrange the mackerel in the pan, then set the heat to medium.
Just before it boils, turn the heat down to low. Cover and simmer for 5 minutes. Next, ladle a small amount of the simmering liquid into a small bowl and mix in the miso until it dissolves. Add the dissolved miso to the pot and gently stir to make sure the miso is evenly distributed.
Use a spoon to ladle the simmering liquid evenly over the pieces of fish. Cover with an otoshibuta (drop lid) and cook for 5 minutes over medium heat. The miso can scald easily, so be careful.
When most of the simmering liquid has boiled down, it's done. In a short time, you have made simmered mackerel in a glossy sauce. You can also cut about 5 cm of the white part of a Japanese leek and simmer it with the mackerel, which is also delicious.
Story Behind this Recipe
I've been making miso-simmered mackerel since my high school days. Through trial and error, I came up with the perfect recipe for miso-simmered mackerel!!
You can use any kind of miso you like. Red, white, or kouji miso would all work, so just use the one that suits your taste. Simmering at a little bit higher heat helps the flavors blend and makes it really delicious.