1. Wash the gutted, scaled fish in cold water and pat thoroughly dry with paper towels. 2. Put the oil in a skillet and turn on the heat to medium. When the oil is hot, lightly dredge both sides of the fish in flour and slip into the skillet. Dont overcrowd the pan; if all the fish does not fit loosely at one time, cook it in batches, dredging it in flour only at the moment you are ready to put it into the pan. 3. Brown the fish well on one side, then turn it and do the other, calculating about 5 minutes on the first side and 4 minutes on the second. Using a slotted spatula or spoon, transfer the fish when browned to a deep serving dish broad or long enough to accommodate all of it without overlapping. Do not pour out the oil in the skillet. 4. With a well-sharpened knife, make two or three diagonal cuts on both side of the fish. be careful not to tear the skin, and avoid cutting into the flesh. 5. Put the chopped onion into the skillet that still contains the oil in which you cooked the fish. Turn on the heat to medium and cook the onion until it becomes colored a pale gold. 6. Add the vermouth and the orange peel. Let the vermouth bubble gently for about 30 seconds, stir, then add the orange juice, lemon juice, salt, and a few grindings of pepper. Let everything bubble for about half a minute, stirring two or three times. Add the chopped parsley, stir once or twice, then pour the entire contents of the skillet over the fish in the serving dish. 7. Allow the fish to steep in its marinade at room temperature for at least 6 hours before refrigerating. Plan to serve the fish no sooner than the following day. Do serve it within 3 days at the latest to enjoy its flavor at its freshest. Take it out of the refrigerator at least 2 hours before bringing to the table to allow it to come to room temperature. Before serving, garnish it, if you like, with fresh slices of orange. ~--