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Thanks to a leasing quirk and his own fondness for noodles, Nirun “Nicky” Vongpukkeaw is a big man on his block in Arlandria. He started small—smaller than most—when, more than a decade ago, he bought Po-Siam, a blink of a restaurant wedged into a space the size of a newsstand. The restaurant’s success was bound to the dimensions of its location, so when a bigger spot opened up across the street four years ago, Nicky took it. Po-Siam glistened in its new digs, replete with a full-service bar (mango daiquiris!) and enjoyable bathrooms. But Nicky still had a lease on the old space, so he opened up Po-Thai and became his own competitor, a Thai food minimogul in a neighborhood so diverse that you can eat authentic pupusas and then go see Doc Watson without ever having to move your car. Today, Nicky says he serves Thai immigrants from as far away as Denver who make a point to stop in NoVa and marvel at his noodle soups.

The differences between the two restaurants are not just cosmetic, though the distinction between the loyalists of each seems to fall along aesthetic lines; Nicky says Po-Siam caters to families, whereas college-age types are fond of the slightly cheaper, significantly more dank Po-Thai. Together, the restaurants’ menus fairly represent Thai cuisine from the ground on up.

The food at Po-Thai is modeled after the street-vendor fare Nicky remembers from his youth, and clearly the restaurateur has retained his native sensibilities despite the years he spent cooking in the kitchens of swank local hotels and country clubs. Designwise, the only concession the restaurant makes to up-market tastes is the single fake rose that adorns each table. The staff is terse. And, as I’d assume is also the case when dining on the streets of Bangkok, the food ranges from tossed-off to sublime. Spring onion dumplings are doughy and undergrilled. On the two occasions when I try to order fish salad, I’m told, “We don’t have that,” in a way that suggests I’ve misread the menu.

The prickly service is part of the restaurant’s appeal—would you expect any different at the spiritual cousin of an American diner?—and often the seemingly tossed-off dishes are what you’ll remember most. The spicy pork is just a plate of meat (I have to ask for rice), but there’s a ridge of fat on just about every bacon-thin slice; pass each sticky bite through a bowl of hot sauce and I guarantee there’ll be nothing left to bring home. The soups are even better. The duck submerged in a tangle of rice noodles tastes as if it’s been simmering in spices for days. What the menu bills simply as hot and sour soup comes adorned with curlicues of tail-on shrimp; the hot and cool flavors in the broth vibrate against each other; and lining the bottom of the bowl is perhaps the broadest noodle in Arlandria, a sheet of wiggly pasta that’s been folded over so many times that you have to work to discover how thin it really is.

Across the street, Po-Thai’s idiosyncrasies aren’t as immediately evident, but they’re there. Regional mainstays sprinkle Po-Thai’s voluminous menu (if you haven’t had pad Thai in a while, here’s the place to revisit it), but they’re not always what you’d expect. We don’t even recognize the spring rolls at first; cloaked in tamarind sauce and stripes of hot mustard, the plump, steamed rods overflow with sausage, sprouts, and crab meat. Keep it simple when you’re ordering salads; the duck salad is muddled with bits of ham, and the catfish salad is made with maw instead of flesh.

Soups are the forte of Po-Siam’s kitchen, as well. They’re served in communal, doughnut-shaped dishes that resemble upturned cake pans. One night, we share a clear, mellow broth threaded with ground pork, clear noodles, and wilted greens; another night, it’s a searing seafood-based elixir spiced with lemon juice, bay leaves, and chili. On my last visit, the people at a neighboring table pass me over a bowl of their tom kha gai, a creamy, coconut-milk and chicken soup scented with lemongrass. There are more than 10 soups on the menu now, and soon there will be more.

Ruling his block has given Nicky the itch to expand beyond its boundaries, but first he thinks he needs to shrink. Later this summer, when his lease runs out, he plans to close Po-Thai and search for locations elsewhere. When that happens, Po-Siam will absorb its sister’s menu as well as its staff. Nicky promises that the extra kitchen help won’t spoil the broth. (I had to ask.)

Po-Siam, 3807 Mount Vernon Ave., Alexandria, (703) 548-3925.

Po-Thai Noodle House, 3838 Mount Vernon Ave., Alexandria, (703) 548-9457.

Hot Plate:

Good, old-fashioned stinginess may be one of the few things that elicits scorn more certainly than lamely co-opted hipness. So it’s a wonder that Xando has been spreading like mushrooms. If I were to give an award to an establishment based on the volume of hate mail I get about it, Xando would win hands down. Most of the venom pertains to atmosphere (the gist: the coffee-bar-with-food-and-booze concept is a good one, but environments quit being rarefied when they multiply) and, as one reader puts it, “that fucking name.” (The register guy at the Capitol Hill location clears up the moniker issue: “X and O,” “as in hugs and kisses,” is the root of the name, but it’s pronounced “zando.”) But the most vicious mail comes from a woman who requests that we send a reporter to Xando “to slap them around.” At issue is a cheese “kissadilla” that she found puny. Indeed, the one I sample is small, but it’s also bad: It’s stuffed with beans and liquidy cheese, and while there’s some crunch to one side of the tortilla, the other side, much like the croutons on my salad, is not crisp at all. It’s not the kind of meal that should make one violent. But it’s also not the kind of thing I’d ever care to eat again.

Xando Coffee and Bar, 301 Pennsylvania Ave. SE, (202) 546-3345. —Brett Anderson

Eatery tips? Hot plates? Send suggestions to banderson@washcp.com. Or call (202) 332-2100 and ask for my voice mail.