Heat the oil to 400 degrees F in a deep-fryer. Allow about 1 hour for the oil to come up to temperature and be sure to fry in an open area.
Remove the turkey from the refrigerator and let come up to room temperature. Pat the turkey dry with paper towels. Whisk together the garlic powder, onion powder, paprika, salt, black pepper and cayenne in a small bowl.
Sprinkle the turkey generously inside the cavity and out with the spice rub. Use your fingers to separate the skin from the breasts and rub the spice mixture into the meat. Carefully and slowly lower the turkey, legs pointing down, into the deep-fryer and fry until a thermometer reads 165 degrees F when inserted into the thickest part of the thigh, about 3 minutes per pound, 42 to 45 minutes.
Transfer the turkey to a baking sheet lined with a wire rack and let rest for 30 minutes before carving. Do not cover with foil while it rests or you will lose the beautiful crispness of the skin. Place on a serving platter and garnish with fresh herbs.
NotesCook's Note: To measure the amount of oil needed to fry the turkey, put the turkey in the fryer, add water to top of turkey, and mark the water line with a crayon or marker. Remove the turkey and the water line will indicate how much oil will be needed to fry your turkey. Having too much oil can cause a fire. The pot should not be more than 3/4 full or the oil could overflow when the turkey is added. Dry the fryer before adding the oil.