Start preparing the pork belly the day before cooking. Using a mortar and pestle, pound the fennel seeds, salt, chilli flakes, peppercorns, garlic and rosemary together to make a paste. Rub the paste on to the inside of the pork belly.

Roll pork belly lengthways and, using butcher's twine, tie the meat at 2½ centimetre intervals to hold it together. Cover with cling film and leave in fridge at least overnight.

Remove prepared porchetta from fridge and uncover. Season with fine salt all over the skin. Leave for one or two hours to draw out moisture. Wipe with a clean, damp cloth to remove salt.

Half an hour before cooking, preheat oven to 150C. Place porchetta on a rack inside a baking tray. Put in oven to cook for 2½ to three hours. If, after this time, the skin has not crackled, increase the heat to 200C for 15 minutes. Remove from oven and leave to sit at least until warm.

To serve, remove string and cut pork into one-centimetre slices using a serrated knife. Serve with chimichurri.