Mix the zest, juice, garlic, chopped rosemary and Dijon mustard together and rub onto the pork. Season with salt and pepper and let marinate for at least 4 hours.
Preheat the grill. Brush the grates with oil to prevent the pork from sticking. Remove the pork from the marinade and place on the hot grill. Cook for 5 minutes on each side of the tenderloins.
Carefully lift the grill grate and pork from the grill and set on ceramic trivets or red bricks. Drain the soaked fresh rosemary and place it directly on the hot coals. Replace the grill grate and then cover on the grill. Leave the lower vents open halfway and close the top vent so you can just see the smoke coming out. Smoke the pork for 15 minutes and then close the vents completely to kill the fire, but keep the pork warm. Let rest for 10 minutes.