Dakgangjeong (닭강정 / Korean Sweet, Crunchy Fried Chicken)

Mix the chicken pieces, salt, and black pepper in a large bowl. Transfer to a large zipper-lock 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.

Place a large mesh strainer over a bowl.

Heat 2 inches vegetable oil in a large, deep pan or wok over medium-high heat until it reaches about 340°F, 8 to 10 minutes. 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. 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, until all sides are light golden brown and crunchy, 10 to 12 minutes. As each piece is done, transfer it to the strainer. Once the chicken has drained, transfer it to a large bowl. Repeat with the rest of the chicken, making sure to bring the oil back up to 340°F between batches.

Return the oil to 340°F over high heat and 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, until all the chicken pieces are dark golden brown and very crunchy, another 10 to 13 minutes. Transfer the chicken pieces to the strainer or a rack to drain, then place in a large bowl.

If using the peanuts, place them in a slotted spoon or a small 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.

Mix the rice syrup, soy sauce, sugar, vinegar, and mustard in a small bowl.

Heat a large pan or wok over medium-high heat. Add the oil, garlic, ginger, and chili peppers and stir for 30 seconds to 1 minute, until the garlic is a little crispy and fragrant. Add the soy sauce mixture and stir. 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 finish the chicken.

Add the chicken and peanuts (if using) to the bubbling sauce and toss with a wooden spoon to coat nicely. Sprinkle with the toasted sesame seeds and a few teaspoons crushed red pepper flakes (if using). Transfer to a large plate or platter and serve. The chicken will remain crunchy for several hours if left at room temperature, or you can cover and refrigerate it for up to 3 days.