Koikoku (Long-Simmered Carp Miso Soup)

Bring 1.5L preparation water to a boil and immerse 5 bone-in carp pieces and 1 cleaned head for 4 to 5 minutes.

Drain and rinse with the remaining cold water, gently removing white coagulated residue and loose scales.

Arrange the carp pieces and head in one layer in a heavy pot and add 100ml sake and 1750ml soup water.

Bring to a boil over high heat, skimming gray foam while leaving clear flavorful oil.

When little foam remains, reduce to medium-low.

Dissolve 1 teaspoon sugar and 30g miso in a ladle of broth, return it to the pot, and simmer gently with the lid slightly ajar for 2 hours without vigorous boiling.

Grind 10g miso and 20g cooked rice in a mortar until no grains remain.

Thin gradually with 2 ladles of broth, stir the mixture into the pot, and sweep the bottom once slowly to prevent sticking.

Maintain the same gentle simmer for another 50 to 60 minutes.

If the level drops enough to expose the fish, add a little hot water. Confirm the thickest flesh is at least 75°C and separates easily with chopsticks.

Reduce to the lowest heat and dissolve the remaining 60g miso into the broth gradually, tasting as it is added.

Warm for only 3 minutes without a hard boil, then divide carp and broth among 6 bowls.