How to Make It
Place the pork loin on a rimmed baking sheet. Season generously all over with 1/4 cup of the salt, then sprinkle the skin with the remaining 1/4 cup of salt to create a thin layer of salt over it; be sure to push the salt into the crevices in the skin at each score. Refrigerate uncovered overnight.
Let the pork stand at room temperature for 3 hours. Preheat the oven to 275°. Set a rack in a large roasting pan. Using a damp towel, brush the excess salt off the roast, then transfer to the pan skin side up. Bake for about 1 hour and 30 minutes, until an instant-read thermometer inserted in the thickest part registers 115°.
Increase the heat to 450° and continue to roast for about 50 minutes longer, until the skin is crisp and an instant-read thermometer inserted in the thickest part registers 135°. Transfer the roast to a carving board and let rest for 30 minutes. Remove and discard the ties. Using a sharp serrated knife, slice the meat and serve.