If possible, refrigerate uncovered in the fridge for at least 12 hours to let the skin dry out.
Let porchetta sit at room temperature for 2 hours before cooking.
Preheat oven to 500°F. Season porchetta with salt.
Roast on rack in baking sheet, turning once, for 40 minutes.
Reduce heat to 300°F and continue roasting until an instant-read thermometer inserted into center of meat registers 145°F, 1 1/2-2 hours more.
If skin is not yet deep brown and crisp, increase heat to 500°F and roast for 10 minutes more.
Let rest for 30 minutes. Using a serrated knife, slice into 1/2" rounds.
Bon Appetit!
This recipe is from Epicirious.com and based on a 5-6lb roast. For either lighter or heavier roasts, adjust based on the internal temperature for doneness.