To track down Tokyo's best Thai street food, you need to step out of your comfort zone. The search may lead to pungent backstreets, brash suburban malls or hole-in-the-wall stores redolent of lemongrass and durian. In the case of Montee, the trail takes you deep underground.

It's one of those locations you'd never happen upon by chance. A dank stairwell curves down from street level to a subterranean passage known to few but the locals. Lined with cheap sake counters, noodle joints, old-style barbershops and fortune-tellers' booths, it feels like entering a manga from the 1970s.

In fact you're in the heart of Asakusa, just a few meters below the tourist shopping streets and steps away from the subway station but well off the modern map of the city. Hold on to your hat, though: This is just the transit lounge. Once you're through Montee's front door — not hard to spot with its striped tricolor flag and giant inflatable Singha beer bottle — you'll be transported out of Tokyo altogether.