It is barely 10am and the queue outside Onigiri Bongo already stretches around the block. Some of the 30 or so early-bird diners sit on stools, sipping green tea and poring over laminated menus.

For decades nori-wrapped rice dish was mainly a snack eaten at home or in a bento, but now it has come into its own It is barely 10am and the queue outside Onigiri Bongo already stretches around the ...