I found it thanks to Kim Dallas, an American expatriate from Nebraska who has lived in Chengdu for a few years and has studied the local cuisine.

The idea was dreamt up by an expatriate Indian physics professor from the University of Maryland who, travelling back home, found himself harassed by endless extortion demands.

The measures have been taken solely against the Protestant churches, which cater for refugees from Sudan and Iraq and expatriate workers, as well as for Syrians.