In a gallon zip-lock bag, combine the buttermilk, Cajun seasoning, and garlic powder. Add the chicken wings, seal, and massage the bag until every wing is fully coated. Place the bag in a bowl and refrigerate overnight or for at least 12 hours.
When ready to fry, heat the oil in a double burner cast-iron pot to 350°F. Use a thermometer and maintain the temperature throughout frying.
In a separate gallon zip-lock bag, combine the Louisiana Fish Fry, gluten-free flour, cornstarch, garlic powder, Cajun seasoning, and onion powder. Seal and shake to blend.
Working in batches of 6 to 8 wings, remove the wings from the marinade and let the excess drip off. Place them in the coating bag, seal, and shake until fully and evenly coated.
Fry the wings in batches for 8 to 12 minutes until golden brown and cooked through to an internal temperature of 165°F. Don't crowd the pot.
Remove the wings and place on a wire rack to drain. The wire rack keeps air circulating around the wings so the crust stays crispy rather than steaming and going soft.
Serve hot with your favorite dipping sauces.