1Prepare the Tare Sauce: In a small saucepan, combine 60g Koikuchi soy sauce, 60g Mirin, 60g Sake, 30g Sugar, and 30g Dashi stock. Bring to a simmer over medium heat, stirring until the Sugar dissolves. Reduce heat to low and let it gently thicken for about 10-15 minutes, until it coats the back of a spoon. Set aside.
2Prepare the Tsukune Mixture: In a large bowl, combine 500g Ground chicken thigh, 30g Panko breadcrumbs, 50g Egg, 30g finely chopped Scallion, 10g grated Ginger, 15g Koikuchi soy sauce (for tsukune mixture), 15g Sake (for tsukune mixture), 15g Mirin (for tsukune mixture), 5g Sugar (for tsukune mixture), 10g Cornstarch, and 5g Sesame oil. Mix thoroughly by hand until the mixture is very sticky and well combined, about 3-5 minutes. This ensures a good bind for the meatballs.