Cut the chicken into bite-sized pieces, sprinkle with salt and sake, and let it sit for a few minutes. Then, coat it with potato starch.
Peel and finely grate the daikon radish. Thinly slice the green onion, then set both aside.
Prepare the Dashi Soup by combining all the ingredients in a medium pot and bringing it to a boil for a couple of minutes. Keep it warm.
Heat oil over medium heat and deep-fry the chicken until fully cooked.
Place the chicken in the soup, let it cook for a minute, then serve in bowls. Top with grated daikon radish and sliced green onion.