Heat the grill. Rub the lighter side of each fish with oil. Heat an ovenproof non-stick frying pan and put the fish in, cook for 1 minute and then brush the top of the fish with oil, and put the pan under the grill (mind the handle) until the fish skin blisters and bubbles, and the flesh is cooked, about 5-10 minutes depending how big they are. Remove the pan, slide each fish onto a hot plate and lift off the top skin carefully. Add a large knob of butter to the pan, add the chilli, cook for 1 minute then add the vinegar and bubble for a few seconds. Add the parsley, swirl the pan and then spoon the butter over the dab. Serve with more parsley if you like, and the greens and potatoes.