Marinade Chicken. In a bowl mix the lemonade, oregano, oil, salt and pepper. Make small slices into the chicken about 0.5cm down. Add the chicken to the marinade bowl, cover and marinade in the fridge for 8 hours or overnight.
Preheat oven to 180ºC. Drain chicken and discard the marinade. Place the chicken on a baking sheet and bake for 25 minutes. Place lemon slices on chicken for the final 10 minutes of cooking.
Whilst the chicken is cooking, take a large saucepan and fill a third of it with vegetable oil. Heat the oil to 180ºC. *Always take care when around hot oil. Do not leave unattended. Do not heat on or around gas hobs*
Pull apart the onion slices to make rings and add to a bowl. Add the milk to the bowl. Put the flour on a plate and season with salt and pepper. Remove the rings from the milk and toss them in the flour until coated.
Line a place with kitchen tissue roll. Slowly drop the onion rings into the hot oil, not too many as they will stick together and won't crisp properly. Fry the onions for a couple of minutes, until they're golden brown and crisp, then remove with a slotted spoon and put them on the prepared plate.
Allow the oil to come back up to temperature before frying the rest of the onion rings in batches. Sprinkle them with sea salt once done and serve them with the cooked chicken. Optionally serve with a side salad.