Brown onions in butter, and add parsley, tomatoes and white wine. Let this simmer for half an hour, and then pass it through the tammy. Then fry mushrooms, and add them and their liquor to the sauce, thickening it, if necessary, with a little cornflour. A great improvement is a little liebig. Place your fish in the oven, and cook it gently in butter, with pepper and salt. When it is done, serve it with the sauce poured over it.
Attributed to Madame Vandervalle.