Mix together the buttermilk and hot sauce in a large bowl then add in the chicken pieces taking care to make sure they are esch covered with the mixture. Let the chicken marinate here for at least 4 hours.
To bread the chicken.
Work with one piece at a time. Take a chicken thigh and dredge it in the flour mixture taking care to shake off any excess flour. Place the flour-coated chicken thigh in the egg mixture and cover both sides before returning to cover it with flour again and then on to the plate to rest. Continue until all the chicken is breaded.
Fry the chicken.
Pour a couple of inches of oil into a high walled skillet then heat to 350ºF. The temperature dial of your burner should be around medium. Gently lower pieces of chicken into the oil using a pair of tongs. Add as many pieces as you can fit without crowding and cook them about 4 ½ minutes per side before removing them to rest on a rack.
Make the chili oil.
Place the cayenne powder, garlic powder, onion powder, paprika and brown sugar into a heat-proof bowl then carefully remove ½ cup of the cooking oil from the skillet and add it to the bowl along with the spices. Stir to mix well and let the oil cool.
Spice up the fried chicken pieces
Either dip the fried chicken pieces into the bowl of chili oil to cover them or use a brush to brush it over them. Either way make sure to stir the oil up once in a while to keep the spices throughout it as it does settle to the bottom of the bowl.
Put the sandwich together.
Pile shredded lettuce on the bottom of the bun, add 2 pieces of the spicy chicken then top with a generous serving of pickle chips.
Play with the cornstarch to flour ratio. I used 50/50 here to get a very crisp crust. You could use also try 25% corn starch for more of a traditional crust.
Make it a lighter meal. I wanted these sandwiches to be hearty and filling so I used 2 pieces of thighs for each sandwich, but you can definitely use one per sandwich if you're looking for a lighter meal. Either half everything in the recipe except the lettuce, buns and pickle and feed 4, or double the lettuce, buns and pickle and feed 8.
Try chicken breasts. If you're not into dark meat you can try this with chicken breasts. Halve the breasts down there length so it looks like you have two thin chicken breasts then go from there.