ULTIMATE KOOL-AID: ¿Por Qué No? co-owner Bryan Steelman pours aguas frescas with employee Heidi Lieberman.

I disagree with JB, but many don't. Taquerias attract a particularly rabid strain of connoisseur, and it's safe to say that many will call foul on ¿Por Qué No? It's a newish taqueria owned by a white couple, frequented by a largely—but by no means entirely—white clientele, and it charges higher-than-average taqueria prices. That said, there's a restaurant law, often unheeded, that you get what you pay for, and ¿Por Qué No? delivers the goods and then some. And in a neighborhood not known for its Mexican food, it fills a niche.

"Niche" may be the word on your mind when you walk in; the place seats 20 and change. Folksy knickknacks and distressed tables fulfill the decorative requirements without veering into pastiche, and the effect is charming. Jugs of aguas frescas—watermelon, hibiscus, an irresistible raspberry-and-mint potion—line the tiny bar. All are $2, and, thankfully, none suffers from heavy sugaring.

The menu is as diminutive as the surroundings, and as carefully composed: Half a dozen tacos, plus enchiladas and sides, and specials like excellent, delicately fluffed tamales. Chef Mark Saldaña's treatments border on the reverential: Tortillas are handmade; chips are fried on-site. The tweaks are in the details, like line-caught fish for the tacos ($3.50 for seafood, otherwise $2.50), and Carlton Farms pork for the carnitas. The effect is akin to watching high-definition television: One recognizes familiar flavors and textures, but they're startlingly detailed and fully realized.

Pollo verde, chicken slow-cooked in tomatillo salsa, is a dish typically consigned to a slow death by steam table. Here it tingles with the fruit's lemony zing and the gentle nip of cilantro. ¿Por Qué No?'s tinga, typically a chili-fired chicken or pork stew, substitutes shredded beef in a flavorful broth. It makes for a disturbingly succulent taco, and come weekend brunch it often makes a reprise with eggs and tortillas.

Side dishes are equally basic and delicious: a no-surprises guacamole bolstered by those addictive housemade chips, superb pinto beans, and a peppery ceviche based on whatever wild fish is available. If there's a disappointment, it's the house salad, served with a silky but bland tomatillo-avocado dressing. Compared with the other dishes, it's merely fine.

¿Por Qué No?'s upscale street food isn't for everyone. Unsurprisingly, the cries of "Yuppie!" have only begun to resound across Mississippi Avenue, the same kind of complaint that dogged Taqueria Nueve—a restaurant that, on the surface, shares many attributes with ¿Por Que No?—when it opened on Northeast 28th Avenue back in 2000. I'm undecided on the divisive and deeply emotional issue of gentrification, for many reasons. But I do know great cooking when I taste it, and ¿Por Que No?'s got it in spades.