b'TO PREPARE THE ORANGE-GINGER SAUCE:Cook the extra virgin olive oil in a saucepan over high heat for 1 to 2 minutes. Reduce the heat to medium, add the onion and ginger, and cook for 1 to 2 minutes. Add the orange zest and garlic. Cook 1 more minute, stirring well; add the optional chopped sole, and cook 1 more minute. Increase the heat to high and add the sherry. Stir well and cook for 1 to 2 minutes until reduced by half. Add the orange juice and stock (or stocks). Bring to a boil over high heat, cover, then reduce the heat to medium-low and cook for 25 minutes. Strain the sauce into another saucepan and dispose of the strained solids. Bring the liquid to a boil over high heat, then reduce the heat to medium and cook for 10 to 15 minutes until it thickens to a sauce-like consistency and coats the back of a spoon. The sauce can be made up to this point the day before.It will keep fresh in the refrigerator for 2 days.Just before serving, add the optional sections of peeled orange and the butter to the orange-ginger sauce. Cook over low heat for 1 to 2 minutes and stir gently until the butter has completely melted into the sauce and the orange sections have warmed through.TO SERVE:Place a sole fillet in the middle of each dish and top with the orange-ginger sauce. Sprinkle the chopped parsley over the sauce, and serve.64'