Prepare 1½ lb boneless, skin-on chicken thighs by cutting each into 2-inch (5-cm) pieces. Season with ½ tsp Diamond Crystal kosher salt and ⅛ tsp freshly ground black pepper.

Grate the ginger and measure ½ tsp ginger (grated, with juice). Add it to a large bowl. Mince or press 1 clove garlic and add it to the bowl.

Add ½–1 Tbsp soy sauce, ½ Tbsp sake, and ½ tsp toasted sesame oil to the ginger and garlic. Whisk to combine.

Add the chicken to the marinade and mix it with your hands. Cover and marinate in the refrigerator for 30 minutes.

Prepare the oil for deep-frying. Pour about 3–4 cups neutral oil into a heavy-bottomed pot and heat it to 325ºF (160ºC) over medium-low heat.

Dredge the chicken pieces in separate piles of 2 Tbsp all-purpose flour and 2 Tbsp potato starch or cornstarch. Lightly coat a piece of marinated chicken in the flour and dust off the excess, then dredge it in the potato starch and shake off the excess.

Check that the oil temperature has reached 325ºF (160ºC). Gently add 3 to 5 chicken pieces at a time to the hot oil. Deep-fry for 90 seconds, or until the chicken is a light golden color. Transfer to a wire rack to drain the excess oil.

Raise the oil temperature to 350ºF (180ºC). Place the first 3 to 5 pieces of rested chicken back into the oil and deep-fry for 45 seconds, or until the skin is golden brown and crispy. Transfer them to the wire rack to drain the excess oil.

Serve the chicken hot with lemon wedges and a dipping plate of Japanese Kewpie mayonnaise. Optionally sprinkle shichimi togarashi on the mayo.