Pat the pork belly dry with paper towels and put it in a dish or pan. Mix the sugar and salt in a small bowl and rub both sides of the pork with the mixture. Cover with plastic wrap and refrigerate for at least 6 hours, but no more than 12 hours.
Unwrap the pork belly, rinse off the sugar and salt, and pat dry. In a spice grinder, grind the rosemary, fennel s