When you’re ready, brush the grill lightly with oil. Heat the barbecue to a medium-high level.
Score the skin slightly, and brush the sole with oil. Sprinkle with salt, pepper, and a little of the lemon juice leftover from the sauce.
Grill for about 10 to 15 minutes – don’t turn to avoid breaking up the fish.
The fish should be cooked thoroughly and come away easily from the bone.
As the fish cooks, warm the lemon sauce in a small saucepan over a low setting.
Add the spinach and parsley as it warms, until the vegetables wilt.
Add the capers last.
Remove the fish from the grill, and divide into portions.
Serve topped with lemon caper sauce.