Pat the belly dry and place into a large plastic bag. Mix together the syrup, sugar, kosher salt, pink curing salt and pepper, and massage into the belly until mostly absorbed. Seal the bag and refrigerate for 7 days.
After 7 days, rinse the belly and pat dry. Preheat the oven to 250 degrees F.
Place the belly, fat-side up, on a rack on a roasting pan and roast until the internal temperature reaches 150 degrees F, about 2 hours.
Slice and cook as desired, or wrap well in plastic wrap and keep for a week in the fridge or 3 months in the freezer.