In a sturdy roasting pan, heat the olive oil until shimmering. Season the roast with salt and pepper and cook over moderately high heat until browned all over, 10 to 12 minutes. Add 1/2 cup of water to the pan. Roast the pork for about 2 hours, basting occasionally and adding 1/4 cup of water to the pan each time you baste. The meat is done when an instant-read thermometer inserted in the center of the roast registers 160°. Transfer the pork to a baking sheet and let stand for 10 minutes. Pour any pan juices into a measuring cup and skim off the fat.