Step 1: Place fish in microwavable dish just large enough to contain fish. Pour over balsamic vinegar unti halfway up the fish. Leave for two or three hours then turn fish over and leave for a while. Cover with cling film and cook in microwave for a couple of minutes, testing with a skewer. When cooked, eat with bread and butter. Don’t waste the gravy, it is lovely soaked up with the bread and butter.