Preheat the oven to 180C/350F/Gas 4. For the southern fried chicken, remove the skin from the chicken pieces and slash the flesh with the tip of a sharp knife.
Lightly whisk the egg whites together in a bowl and add the chicken, mixing well to coat. Place all the gluten free breadcrumbs, lemon zest, cayenne pepper, celery salt, dried thyme, dried oregano, cracked black pepper and sea salt into a bowl and mix until well combined. Dip the chicken pieces in the breadcrumb mixture, ensuring all of the chicken is well coated.
Heat the vegetable oil in a deep fat fryer to 170C/338F, checking the temperature with a digital thermometer. Alternatively, half-fill a deep, heavy-based pan with the vegetable oil and heat until a breadcrumb dropped in sizzles and turns golden-brown in 30 seconds. (CAUTION: Hot oil can be dangerous. Do not leave unattended.)
Cook the chicken, a few pieces at a time, in the oil for 6-10 minutes (depending on the size of each piece), or until golden-brown and crisp, turning the pieces over occasionally. Remove with a slotted spoon and place onto a baking tray, then cook the chicken in the oven for 15 minutes, or until cooked through (the juices should run clear when the chicken is pierced in the thickest part with a skewer). Keep warm.