Mackerel Simmered in Miso (Saba no Misoni)

1. Score the skin side of the mackerel fillets a few times. Pat dry. 2. In a wide, shallow pot or deep skillet, combine water (or dashi), miso paste, mirin, sake, sugar, and grated ginger. Whisk until the miso is fully dissolved. Bring to a gentle simmer over medium heat. 3. Carefully add the mackerel fillets to the simmering sauce, skin-side up. Ensure the fish is mostly submerged. Some recipes recommend placing kitchen parchment paper directly on top of the fish (otoshibuta) to help it cook evenly. 4. Simmer for 15-20 minutes, basting occasionally with the sauce, until the fish is cooked through and flaky. 5. Serve immediately with the sauce, garnished with julienned ginger and chopped scallions if desired. Best served with steamed rice.