• Cut each chicken thigh into 2-inch pieces and season with salt and freshly ground black pepper.
• Grate the ginger (you will only need ½ tsp) and mince the garlic.
• In a large bowl, combine the ginger, garlic, soy sauce, sake, and sesame oil. Whisk it all together.
• Add the chicken to the bowl and mix it with your hands. Cover and keep in the refrigerator to marinate for 30 minutes.
• Pour the oil into a heavy-bottomed pot (such as a Dutch oven) and heat it to 325ºF (163ºC) on medium heat.
• Meanwhile, prepare the potato starch and all-purpose flour in separate piles.
• First, lightly dredge each marinated chicken piece in the flour and dust off the excess flour. Then, dredge it in the potato starch and remove the excess starch. Continue with the remaining chicken pieces.

First deep-frying

• When the oil temperature has reached 325ºF (163ºC), gently submerge each chicken piece in the oil. Do not overcrowd the pot; add only 3-5 pieces at a time. If you put too many pieces in at once, the oil temperature will drop quickly, and the chicken will end up absorbing too much oil.
• Deep-fry for 90 seconds, or until the outside of the chicken is a light golden color. If the chicken browns too quickly, then the oil temperature is too high. Either put a few more pieces of chicken in the oil or lower the heat. Controlling the oil temperature at all times is very important for deep-frying. Transfer the chicken pieces to a wire rack to drain the excess oil.
• The residual heat will continue to cook the chicken as it rests on the wire rack. Continue deep-frying the remaining chicken pieces. Between batches, pick up and discard the crumbs in the oil with a fine-mesh sieve. This keeps the oil clean and prevents it from becoming darker.

Second deep-frying

• Now, heat the oil to 350ºF (177ºC). Place 3 to 5 pieces of the resting chicken back into the oil and deep-fry for 45 seconds, or until the skin is golden brown and crispy. Transfer them to a wire rack to drain the excess oil. Continue with the remaining chicken pieces.
• Serve the chicken hot. Karaage is often served with a wedge of lemon and Japanese mayonnaise. Sprinkle shichimi togarashi for a bit of spice, if desired.