It's hard to think of a food that has achieved greater upward mobility -- at least here in Japan -- than goi cuon, those delectable, rice-paper-wrapped spring rolls that almost single-handedly define Vietnamese cuisine. Over the past decade, they have moved out of the minority ghetto of back-street ethnic restaurants and into the cash-flush watering holes of the cultural mainstream.

We are the first to applaud, now that nama harumaki (as they are known in Japanese) can be found on the menus at trendy Harajuku cafes, the swish, late-night dining bars of Azabu, and even some of the city's more adventurous izakaya. But at regular intervals we do like to journey back to the source, to remind ourselves how they're made in the markets of their homeland.

Time and budget constraints preclude frequent flights to Hanoi or Ho Chi Minh City. But a highly acceptable alternative is just to ride the subway down to Yotsuya Sanchome, to Thien Phuoc, one of the friendliest, funkiest Vietnamese eateries in all of Tokyo.