Make the buttermilk marinade. Add the buttermilk, pickle juice, eggs, hot sauce and salt to a large bowl, mixing to combine. Toss the chicken thighs in the marinade to coat. Marinate for at least 1 hour or overnight in the refrigerator.
In another bowl, mix together the flour, cornstarch, paprika, garlic powder, onion powder, salt, black pepper and cayenne pepper. Dredge the chicken in the flour mixture and let sit for 5 minutes.
Preheat the oil to 350°F in a Dutch oven or large cast iron skillet. Working in batches, fry each cutlet about 3-4 minutes per side or until cooked through. Place on a paper towel–lined plate or wire rack.
Build the sandwiches with your favorite toppings.
Notes
Allow the chicken to reach room temperature before breading and frying. This step has a dual purpose. Firstly, when the chicken is at room temperature, it won't significantly reduce the oil's temperature upon immersion, and secondly, it will cook faster without the risk of overcooking or burning.
Keep the oil temperature consistent throughout the frying process. Fluctuating temperatures can lead to uneven cooking and less crispiness. Adjust the heat as needed to maintain the desired frying temperature.
Fry the chicken in batchesof two to avoid overcrowding, which can lead to uneven frying.