Score both sides of the fillets taken from the fish; put them in a tureen with salt, pepper, chopped up onions, parsley, oil, and vinegar; one hour later drain them from their marinade, roll them in flour, and fry to a fine color, and when firm dress with a tomato Andalouse sauce (No. 550) served separately.
A short entry from Ranhofer that assumes you have the rest of The Epicurean open beside you. Two things carry the dish: a proper vinegar-and-oil marinade, and frying hot enough that the flour coating sets before the thin fillets overcook.
Charles Ranhofer wrote The Epicurean (1894) out of some thirty years running the kitchen at Delmonico's in New York, and the book is organised like a professional reference: numbered recipes, constant cross-references to sauces and garnishes elsewhere in the volume, and almost no explanation for the beginner. This entry sits in a long run of freshwater fish — eels, pike, carp, sturgeon — grouped together in the fish chapters. The "Andalouse" label was a nineteenth-century French kitchen convention marking the presence of tomato and sweet pepper, the two ingredients European cooks associated with southern Spain; the sauce has no documented Andalusian origin and the name is best read as menu geography.