Phobo TAi CHiN.

I've had an enduring obsession with food searches. They have taken me to obscure outposts, led to lasting friendships around the world and immersed me in local history and social customs.

And so it proved with pho, as Gilbert and I went about this throbbing, entrepreneurial city, admiring restored early-20th-century architectural landmarks built during the French protectorate, when the country was called Tonkin and the region was known as Indochina. Gilbert willingly agreed to an ambitious itinerary, which we punctuated with dueling wordplay--"Phobia," "It's what's pho dinner," "pho pas"--as we sought out the most authentic, beef-based pho bo or the lighter, chicken-based pho ga. Alas, our puns were based on the incorrect American pronunciation, "foe." In Vietnamese, it is somewhere between "fuh" and "few," almost like the French feu, for fire, as in pot-au-feu, and thereby hangs a savory shred of history.

We chopsticked our way through slim and slippery white rice noodles, green and leafy tangles of Asian basil, sawtooth coriander, peppermint, chives and fern-like cresses. For pho bo, we submerged slivers of rosy raw beef in the scalding soup to cook just milliseconds before we consumed them. Pho ga, we discovered, is traditionally enriched with a raw egg yolk that ribbons out as it coddles in the hot soup. Both chicken and beef varieties were variously aromatic, with crisp, dry-roasted shallots and ginger, exotically subtle cinnamon and staranise, stingingly hot chilies, astringent lime or lemon juice and nuoc mam, the dark, fermented salty fish …