How China’s dan dan mian noodle dish made its way to Japan and became so popular

There is a choice to be made at this Tokyo noodle bar, and misjudgment could be painful. The laminated menu lists increasing levels of karasa (heat from chilli oil) and shibire (numbing spice from Sichuan peppercorns) on a scale from one to five. There is a level six, too, but that invites an additional fee; any wanton spice masochism must be paid for in hard cash as well as incidental sweat and tears. This is Szechuan Tantanmen Aun, which has been operating in a corner of downtown Tokyo since...