The Potato Roasting Truck
One of the many trucks that prowl around the city, roasting and selling "yaki imo" or roasted sweet potatoes.
The box in the truck's bed it the oven, sometimes doing the roasting in a bed of small black stones.
The trucks drive slowly around, announcing through their loudspeaker "Yaaaki imoooo - yaaaki imoooo...."
(I worked with a guy once who mistook the sound for the Muslim call to prayers.)
My favorite part about the trucks, though, is the smoky smell of burning hardwood, something I'd otherwise miss living in the city.