By Mark Hix
First make the sauce: simmer the shallots in the white wine and vinegar until the wine has evaporated, then add the fish stock and mustard, and simmer until you have a couple of tablespoons of liquid left. Add the cream and simmer until the sauce has reduced by about half and thickened. Add the parsley, season and simmer gently for another minute.
Meanwhile, heat a little vegetable oil