Preheat barbecue to medium-high. Place rosemary sprigs on plank and preheat plank according to package directions.
Place tenderloins on plank, tucking thin ends under. Close lid and cook until internal temperature reaches 160°F (71°C), 30 to 40 minutes. Turn and brush pork with dressing every 10 min.
Carefully remove plank and let pork rest 5 min. before slicing.