In a large stockpot, bring 1 gallon of water to a simmer.
Stir in kosher salt, brown sugar, and Cajun seasoning until fully dissolved.
Add smoked paprika, garlic powder, onion powder, cayenne pepper, black pepper, and bay leaves. Stir well.
Remove from heat and let the mixture cool to room temperature.
In a large brining bag or container, place the turkey and pour in the cooled brine.
Add the cold water, garlic, onion, lemon, orange, thyme, and rosemary.
Ensure the turkey is fully submerged, then refrigerate for 12 to 24 hours.
Before cooking, remove the turkey from the brine, rinse it with cold water, and pat it dry with paper towels.
Proceed with your preferred turkey cooking method.