Heat 4 cups of oil over medium-high heat to 350°F. Tip: Use a thermometer to check the temperature of your oil. If you don‘t have an instant read thermometer, insert a wooden chopstick into the oil. If small bubbles start to appear around the bottom tip of the chopstick, the oil is ready.
First-Fry: Gently submerge 4 to 5 chicken pieces in the oil at a time for the first-fry. Be sure not to overcrowd the pot of oil because it will cause the temperature of the oil to drop.
Fry the chicken for about 2-3 minutes or until the outside of the chicken is a light golden color. If the chicken browns too quickly, lower the heat. Transfer the fried chicken to a wire rack to drain the excess oil. Repeat this with the remaining chicken. Tip: Between batches, use a fine-mesh skimmer spoon to strain and clean the oil of any dark crumbs .
Second-Fry: After all the chicken have been through the first-fry phase, raise the temperature of the oil to 380ºF. Place 4 to 5 pieces of the fried chicken back into the oil and deep-fry for about another 1-2 minutes, 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 while it's still hot. Karaage is often served with lemon wedges and a Kewpie mayo-based dipping sauce.