Culinary Mythology: Chop Suey

I had heard this but never seen anything definitive until reading about it in this book.

ORIGIN OF CHOP SUEY
Various legends have been current. They agree in supposing that a Chinese cook (usually in California), confronted by a demand from exigent diners for food at an hour when everything on the menu was "off," improvised a mixture from leftovers and said that the dish was called Chop Suey, meaning "odds and ends" in Chinese. The identity of the demanding diners varies (in a manner typical of mythology): drunken miners, a San Francisco political boss, railroad workers, a visiting Chinese dignitary, etc.

Anderson (1988) gives the true explanation. Chop suey is a local Toisanese dish. Toisan is a rural district south of Canton, the home for most of the early immigrants from Guangdong to California. The name is Cantonese tsap seui (Mandarin tsa sui), meaning "miscellaneous scraps."

The Oxford Companion to Food by Alan Davidson