Preheat the oven 220°C.
Using a sharp knife, cut small slits through the skin and into the meat, then insert the slivers of garlic into these. Rub the pork all over with approx. 1 Tbsp of olive oil, then rub the skin with salt.
Put the pork onto a wire rack in a roasting tin and cook in the oven for 25-30 mins until the skin is crispy.
Meanwhile, grind the fennel seeds, rosemary and peppercorn, using a pestle & mortar, then mix in the oregano and chilli flakes. Set aside.
Take the meat out and reduce the oven temperature to 150°C.
Remove the wire-rack and put the pork in the middle of the roasting tin. Using a silicon brush, baste the meat and the skin with the cooking juices, then scatter the herb mixture all over, covering the skin well.
Cover the tin with foil and bake for 2-2.5 hours.
Remove the foil after 2 hours - if the crackling needs to be more crispy, turn the temperature up to 220°C again for 10-20 minutes. Be careful not to burn it though!
Put the pork on a serving plate, cover well and rest for 10 minutes before carving. Meanwhile, make some gravy from the cooking juices.