Complete with an oven and an awning, plus a price list and colourful advertising, the truck trundled slowly around the perimeter of a park on a chilly March evening. It paused outside an apartment block, engine idling. A mother and child stopped, and, after a brief exchange with the vendor, they sauntered off with warm sweet potatoes in hand. The truck lingered a moment longer and then slowly drove on. The song, its rising and falling intonation like a lament, started up again: yaki-imo…