Mix all the seasoning together and divide it in half.
Add half of your seasoning to the buttermilk and marinate chicken for 2 hours.
Combine flour, corn starch and the rest of the seasoning.
Coat chicken thigh into flour mixture, and allow to rest for at least 30 minutes.
Heat oil to medium-high
In a small bowl, mix mayo sauce ingredients
Build your sandwich. Toast your buns, spread sauce on both sides, add pickles, add chicken.