Steps

1. Make a cut along the backbone near the belly of the mackerel. Hold the thinner bones with your knife and pull them out by hand.
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2. Make a cut in the thickest part of the mackerel.
   🕒 01:08
3. Pour boiling water over both sides of the mackerel to remove odor and impurities.
   🕒 01:16
4. Add water, Cooking Sake (Rice Wine), Mirin (Sweet Rice Wine), sugar, and plenty of sliced ginger to a frying pan. Bring to a boil over high heat.
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5. Add the prepared mackerel to the boiling liquid and bring back to a boil.
   🕒 03:18
6. Carefully skim off any scum that rises to the surface of the simmering liquid.
   🕒 03:39
7. Reduce heat to low. Take the miso from [B] into a bowl and mix with a small amount of the simmering liquid until dissolved.
   🕒 03:51
8. Add the dissolved miso to the frying pan and mix well.
   🕒 04:23
9. Place a lid on top (otoshibuta) and simmer over low heat for about 10 minutes, being careful not to let the liquid evaporate. [Key Tip!] Making a small hole in the center of the lid will help reduce evaporation.
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10. After simmering for 10 minutes, remove from heat and let it rest until it cools down. [Key Tip!] Resting it allows the sauce to thicken and the mackerel to absorb the flavor as it cools.
    🕒 05:14
11. Add the pre-boiled or microwaved potatoes to the frying pan along with the mackerel. [Key Tip!] When microwaving potatoes, make slits to prevent them from exploding.
    🕒 05:31
12. Cover with an aluminum foil lid and simmer gently over low heat for about 10 minutes, just enough to keep it bubbling.
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13. Remove from heat and let it rest with the lid on until it cools down.
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14. Return to heat and warm through.
    🕒 07:12
15. Arrange the mackerel and potatoes on a plate.
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16. Place a piece of butter on top of the mackerel and potatoes.
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17. Generously spoon the simmering liquid over everything.
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