Prepare the Brine: Combine all of the brine ingredients in a large stockpot, cover, and bring to a boil. Boil for 1 minute, stirring to dissolve the salt. Remove from the heat and cool completely, then chill thoroughly in the refrigerator before using. The brine can be refrigerated for up to 3 days.
Brine the Chicken: Pour the brine into a large container, add the chicken pieces and refrigerate for 8 to 12 hours.
Prepare the Chicken: Remove the chicken from the brine and rinse under cold water. Pat dry with paper towels and let sit at room temperature for 1½ hours.
Prepare the Coating and Dredging Station: Fill a large pot with at least 2 inches of frying oil, place it over medium heat, and heat to 320 degrees F. Place a wire cooling rack on top of a baking sheet. Whisk together the flour, garlic powder, onion powder, paprika, cayenne, and black pepper; divide the mixture between two shallow bowls. In a third shallow bowl, pour 1 quart of buttermilk.
Dredge the Chicken: Dip the chicken thighs into the first bowl of coating, turning to coat and patting off the excess; dip them into the buttermilk, allowing the excess to run back into the bowl; then dip them into the second bowl of shaggy coating. Transfer to the parchment-lined pan.
Fry the Chicken: Carefully lower the thighs into the hot oil. Fry for 11 to 12 minutes, until the chicken is a deep golden brown and cooked through (should register 170 degrees F). Transfer the cooked thighs to the cooling rack.
Fry the Drumsticks: Cook the chicken drumsticks for about 8 minutes, checking for doneness. Transfer to the cooling rack.
Fry the Breasts and Wings: Coat the chicken breasts and wings, then carefully lower them into the hot oil. Fry for 7 minutes for the breasts and 6 minutes for the wings.
Serve and Enjoy: Allow the chicken to rest for about 10 minutes before serving.
