1Begin by preparing the dashi stock. Place the Kombu in the Water in a large nabe pot and let it soak for at least 30 minutes. Gently heat the Water over medium-low heat. Just before the Water boils, remove the Kombu. Increase heat to medium, add the Katsuobushi, and bring to a boil. Immediately reduce heat and simmer for 30 seconds. Turn off the heat and let the Katsuobushi settle to the bottom for 5 minutes. Strain the dashi through a fine-mesh sieve, discarding the Katsuobushi.
2While the dashi is infusing, prepare the Tsukune (chicken meatballs). In a large bowl, combine the Ground chicken, 30g of finely minced Scallion, grated Ginger, Egg, Panko, 15g of Koikuchi soy sauce, 15g of Sake, and Sesame oil. Mix thoroughly by hand until well combined and slightly sticky. Form the mixture into small, bite-sized meatballs.
3Prepare the remaining nabe ingredients. Cut the Napa cabbage into 5cm pieces. Remove stems from Shiitake mushrooms and score the caps decoratively if desired. Trim the base of the Enoki mushrooms and separate into smaller clumps. Cut the Tofu into 2-3cm cubes. Cut the remaining 50g of Scallion into diagonal slices. Wash and trim the Mizuna.