1. Whisk together buttermilk, 2 tablespoons hot sauce, and 2 tablespoons vinegar in a large bowl.
2. Add chicken; toss to coat. Transfer to the refrigerator and let marinate for at least 10 minutes or up to 1 hour, stirring occasionally.
3. While the chicken is marinating, whisk together flour, cornmeal, and cayenne in a shallow dish.
4. Whisk the remaining 1 tablespoon hot sauce and 1 tablespoon vinegar in a small bowl; set aside.
5. Remove the chicken from the marinade and roll in the flour mixture until evenly coated.
6. Heat remaining oil in a large, nonstick skillet over medium-high heat. Add the chicken and cook until golden brown and cooked through (3-5 minutes per side), working in batches.
7. Transfer chicken to a serving platter as it finished cooking and with the reserved hot sauce mixture.