Whisk rice vinegar, sugar, salt, and 110ml water to dissolve.
Coat radish in liquid and leave at room temperature for 24 hours before refrigerating.
Whisk cornflour, salt, baking powder, and pepper in a bowl.
Coat chicken pieces in the mixture and refrigerate on a rack for 1 hour.
Heat oil in a large dish to 175°C.
Mix dry batter ingredients, then whisk in wet ingredients and 235ml water.
Dip chicken in batter and fry for 15-20 minutes until golden.
Simmer soy sauce, vinegar, mirin, sugar, garlic, and ginger in a pan.
Thicken soy sauce with cornflour slurry and bring to a boil.
Simmer red chilli sauce ingredients in a pan for 3 minutes.
Serve chicken with radish and sauces, garnished with chives and sesame seeds.