1.Add ginger, garlic, soy sauce, sake, and sugar to a bowl and combine. Add the chicken, then stir to coat evenly. Cover and refrigerate for at least 1 hour, preferably overnight.
2.Add 1 inch of vegetable oil to a heavy bottomed pot and heat until the oil reaches 360 degrees F. Line a wire rack with 2 sheets of paper towels.
3.In the bowl of chicken, add the potato starch and toss to coat each piece evenly.
4.Using tongs add karaage in batches until the exterior is a medium brown and the chicken is cooked through.
5.Transfer the fried chicken to the paper towel lined rack. If you want the karaage to stay crispy longer, you can fry the chicken a second time, until it's a darker color after it's cooled off once. Serve with lemon wedges on the side.