Preheat the Oven: Preheat your oven to 220°C (430°F).
Prepare the Pork: Using a pestle and mortar, grind the fennel seeds and Celtic sea salt together. Rub the extra virgin olive oil into the pork skin, then apply the salt mixture evenly over the pork.
Prepare the Vegetables: Peel the red onions and slice them into thick wedges. Quarter the garlic bulb. Arrange the onion wedges and garlic quarters at the bottom of a roasting tray, then place the pork rack on top.
Initial Roasting: Roast the pork in the preheated oven until the skin turns brown and crispy, approximately 20-30 minutes.
Lower the Heat: Reduce the oven temperature to 180°C (355°F) and continue to cook the pork for another 20 minutes.
Prepare the Apples: Score the apples along the centre (to prevent them from bursting) and place them in the roasting tray around the pork. Cook for an additional 20-30 minutes until the pork juices run clear and the apples are soft.
Rest the Pork and Apples: Once cooked, remove the pork and apples from the tray and keep them warm.
Make the Sauce: Transfer the remaining contents of the tray into a saucepan through a sieve. Add the white wine to the juices and boil over medium heat for a few minutes until the sauce thickens. Then, add the beef stock and simmer for 15 minutes.
Serve: Serve the pork and apples together, topped with the delicious sauce.