Wow-Wow sauce

Wow-Wow Sauce (sometimes referred to as Bow wow sauce) is a sauce reportedly created by William Kitchiner of London in the early 19th century. It contains port, wine vinegar, parsley, pickled cucumbers or pickled walnuts, English mustard and mushroom ketchup in a base of beef stock, flour and butter. A recipe appears in "Enquire Within Upon Everything" (88th edition, 1894).
It is parodied as a sauce of the same name in the "Discworld" novels of Terry Pratchett. A variant of the above real-world recipe is published in "The Discworld Companion" and "Nanny Ogg's Cookbook".