In a large mixing bowl, whisk together the buttermilk, cayenne pepper, garlic powder, onion powder, Cajun spice, oregano, salt, and ground black pepper. Submerge the chicken tenders in the marinade, ensuring they are well coated. Cover and refrigerate for at least 2 hours, or overnight for maximum flavor.
In a shallow dish, combine the all-purpose flour, paprika, cayenne pepper, and salt. Mix well until all ingredients are evenly distributed.
In a frying pan or deep fryer, heat enough oil to submerge the chicken pieces, about 2-3 inches deep. Preheat the oil to 350°F (175°C). Use a cooking thermometer to ensure accuracy.
Remove the chicken from the marinade, allowing any excess buttermilk to drip off. Dredge each piece in the flour mixture, pressing gently to ensure an even coating. Shake off any excess flour and set aside on a wire rack or plate.
Carefully add a few pieces of coated chicken to the hot oil, being mindful not to overcrowd the pan. Fry for about 5-7 minutes on each side, or until the chicken is golden brown and reaches an internal temperature of 165°F (74°C). Use a slotted spoon or tongs to turn the chicken as needed.
Once the chicken is cooked, remove it from the oil and place it on a plate lined with paper towels to drain any excess oil. Allow the chicken to rest for a few minutes before serving, as this helps retain its juiciness.