2) Brush the fish lightly with oil. Season the outside of the fish with generously with salt and the pepper, to taste. Cook the trout until an instant-read thermometer inserted into the thickest part of the fish registers 58C, turning once, about 5 mins per side. Set aside for 5 mins before serving.
3) Meanwhile make the dressing: Put the vinegar, orange zest, salt and pepper in a medium bowl. Gradually whisk in the oil to make a dressing.
4) Snip off the string or remove the skewer and serve each fish drizzled with some of the dressing.