Prep the vegetables.Peel the daikon and cut it into 1-inch quarter-rounds pieces. Peel the ginger and slice it thinly, about 1 mm thick.
Cook the ginger and chicken.Heat a pot over medium-low heat and add a small drizzle of sesame oil. Add the sliced ginger and sauté until fragrant. Increase the heat to medium, add the ground chicken, and cook while breaking it up well with a spatula until no longer pink.
Add daikon and water.Pour in the water, then add the cut daikon. Increase heat to medium-high and bring to a boil. Skim off any foam that rises to the surface.
Season and simmer.Once boiling, add the sake, mirin, sugar, soy sauce, and dashi. Reduce heat to medium, place an otoshibuta (drop lid* please see FAQ below) on top, and simmer for 20–25 minutes.Otoshibuta is a lid that sits directly on the ingredients, helping the daikon cook evenly and absorb flavor.
Thicken the sauce and finishIn a small bowl, mix the cornstarch and water well. Before the starch settles, slowly drizzle the mixture into the pot while gently stirring with a spatula. Continue stirring until the sauce thickens evenly without breaking the daikon, then simmer for another 1–2 minutes until the sauce is lightly thickened. Turn off the heat and serve warm.