2) Preheat the griddle to 190 to 205C. Meanwhile, brush the trout inside and out with olive oil. Season inside and out with salt and pepper.
3) Place the trout onto the planks belly down and open. Place the planks over indirect heat and leave to cook until the fish reaches an internal temperature of 50C on an instant-read thermometer, approximately 15 to 20 minutes.
4) Remove the planks from the griddle and allow to sit for 5 to 10 minutes before serving as is, or deboning and serving.