Maangchi's Korean Fried Chicken

Directions

1. Make the chicken: In a large bowl, mix the chicken pieces, salt, and black pepper. Transfer to a large zip-top bag, add the potato starch, close the bag, and mix well by flipping the bag over and back again until the chicken is well coated.
2. Place a large fine-mesh strainer over a bowl. In a large, deep pan or wok over medium-high heat, heat 2 inches of the vegetable oil for 8 to 10 minutes, until an instant-read thermometer registers about 340°F. If you don’t have a thermometer, test it by dipping a tip of a chicken piece into the oil. If it bubbles, it’s ready.
3. Carefully add the chicken to the oil one piece at a time, working in batches to avoid overcrowding. Deep-fry, turning the chicken with tongs, for 10 to 12 minutes, until all sides are light golden brown and crunchy. As each piece is done, transfer to the prepared strainer. Once the chicken has drained, transfer to a large bowl. Repeat with the remaining of the chicken, making sure to bring the oil back up to 340°F between batches.
4. Return the oil to 340°F over high heat. Carefully add all the chicken—there’s no need to work in batches this time. The chicken will look a little soggy at first. Deep-fry, turning occasionally, for 10 to 13 minutes, until all the chicken pieces are dark golden brown and very crunchy. Return the chicken to the strainer or a rack to drain, then transfer to a large bowl.
5. If using the peanuts, place them in a slotted spoon or a small fine-mesh strainer, carefully dip them into the hot oil, and fry for 15 to 30 seconds, just until light golden brown. Transfer to a small bowl.
6. Make the sauce and serve: In a small bowl, mix the rice syrup, soy sauce, brown sugar, vinegar, and mustard.
7. Heat a large pan or wok over medium-high heat. Cook the oil, chiles, garlic, and ginger, stirring, for 30 seconds to 1 minute, until the garlic is a little crispy and fragrant. Add the soy sauce mixture and stir to combine. Let it bubble for 2 to 3 minutes, until the mixture is shiny and a little sticky. Remove from the heat if not using right away and reheat until bubbling when ready to serve.
8. Add the chicken and peanuts to the bubbling sauce and toss with a wooden spoon to coat. Sprinkle with the sesame seeds and crushed red pepper flakes (if using). Transfer to a large plate or platter.
9. Make the optional pickled radish side: In a large bowl, mix the water, vinegar, sugar, and salt until the sugar and salt are well dissolved. Add the radish and stir a few times. Transfer to an airtight container or a glass jar. Keep in the refrigerator at least 2 hours before serving.
10. Do Ahead: The chicken will remain crunchy for several hours at room temperature, or cover and chill for up to 3 days. The pickled radishes can be made 2 weeks ahead. Keep chilled.