Lay the pork skin side down on a work surface, with a sharp knife make a few slits in the flesh.
Make a lengthwise slit on the tenderloin.
In a small bowl, mix together the sage, rosemary, garlic, 2 tablespoons of salt and 2 tablespoons of olive oil. Spread the mixture over the exposed surface of the belly, working it into the cuts in the flesh.
Spread some of the of the mixture in the slit of the tenderloin.
Generously sprinkle the fennel pollen over the belly and tenderloin.
Position the tenderloin in the middle of the pork belly.
Roll up the pork belly around the tenderloin and tie with butcher’s twine.
Place in a roasting pan. Make some slits in the skin with a sharp knife, drizzle with olive oil and season with salt and freshly ground black pepper.
Place the pan in the oven and cook for 2 1/2 - 3 hours. The juices should run clear when pierced with a knife.
Remove from oven and allow to rest for 15 minutes, loosely tented with foil. Slice and serve.