Whisk buttermilk, egg and kimchi together in a large bowl. Add chicken, making sure the pieces are coated and submerged in the buttermilk mixture. Cover with plastic wrap and refrigerate overnight.
Combine flour, salt, paprika, cayenne, garlic powder, white pepper and onion powder in a large shallow dish.
Remove chicken from the buttermilk-kimchi mixture and dredge each piece in the seasoned flour. Shake off any excess. Transfer chicken to a plate; let it rest for 15 to 20 minutes, then dredge each piece again in the seasoned flour and place it back on the plate.
Heat peanut oil in a large Dutch oven to a temperature of 325 degrees F. Add all the chicken to the pot and cook 15 minutes for bone-in pieces, 9 minutes for boneless pieces.
Remove chicken from the oil and transfer to a cooling rack set over a paper-towel-lined baking sheet. Let rest for 10 minutes. Heat the oil to 375 degrees F, then fry the boneless pieces for 4 more minutes or bone-in pieces for 10 more minutes.
Remove chicken from the oil and transfer to a cooling rack again set over a paper-towel-lined baking sheet. Let rest for 10 minutes before serving.
Brine the chicken for juicer, more tender fried chicken.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.