Trim off any excess skin and sinew from the chicken, then cut into large bite-sized pieces. Place the chicken in a mixing bowl or plastic bag with garlic, ginger, salt, and pepper. Mix together and allow to marinate for 15 minutes.
Prepare the Korean Sauce and Garlic Mayonnaise by mixing the ingredients together in 2 separate bowls.
Dredge the marinated chicken pieces in potato starch and deep-fry for 3 minutes in cooking oil heated to 340°F. Remove from the oil and place on a cooling rack to rest for 3 minutes. Return to the oil and deep-fry for an additional 2 minutes.
Coat the fried chicken in Korean Sauce. Cover a serving platter with lettuce leaves, then plate the chicken on top. Drizzle with Garlic Mayonnaise.