Steps

1. Make crisscross decorative cuts on the skin of the mackerel. [The Key Point!] Making cuts helps the flavor penetrate, prevents the fish from breaking apart, and stops the skin from peeling off.
   🕒 00:08
2. Blanch the mackerel briefly in boiling water, on both sides, to remove any fishy odor. [The Key Point!] This eliminates the characteristic smell of blue fish.
   🕒 00:23
3. Thinly slice the 1-inch piece of ginger, keeping the skin on. [The Key Point!] Remove any large, knobby parts of the skin.
   🕒 00:39
4. Add 100ml of water to the frying pan.
   🕒 00:53
5. Add 3 tbsp miso, 3 tbsp Mirin (Sweet Rice Wine), 50ml Cooking Sake (Rice Wine), 1 tbsp soy sauce, and 2 tbsp Sugar to the frying pan and mix. [The Key Point!] Mix all the seasonings together first, as it's easy to forget the miso.
   🕒 01:06
6. Bring the seasonings in the frying pan to a boil over high heat. Once the lumps of miso have mostly dissolved, turn off the heat.
   🕒 01:46
7. Arrange the 4 pieces of mackerel, skin-side up, in a single row in the frying pan. [The Key Point!] Overlapping the fish will result in uneven flavor penetration and can cause the fish to lose its shape, so arrange them in a single row.
   🕒 02:04
8. Arrange the thinly sliced ginger over the mackerel.
   🕒 02:19
9. Place a drop lid made from two layers of kitchen paper over the fish. [The Key Point!] Press down to ensure there are no gaps. This technique is crucial for preserving the cooking liquid.
   🕒 02:34
10. Bring to a boil over high heat, then reduce to low heat and simmer for 10 to 15 minutes.
    🕒 02:50
11. Carefully transfer the simmered mackerel to serving plates.
    🕒 04:10
12. Bring the remaining simmering liquid to a boil over high heat, then reduce to low heat and simmer until it thickens.
    🕒 04:20
13. Pour the thickened simmering liquid over the mackerel on the plates.
    🕒 04:48