Lolita’s enchiladas verdes are topped with bright tomatilla salsa and grilled shrimp. (Michael S. Wirtz/Inquirer)

There comes a moment in the life cycle of ethnic foods when a signature dish - be it curry, spring rolls, tortillas or pesto - ceases being ethnic at all.

It simply melts into the proverbial sauce pot of a progressive restaurant scene and reemerges beneath a tuft of microgreens (and no doubt ringed by huitlacoche vinaigrette) as yet another bright color in the palette of the New American menu.

That cycle has come nearly full circle at Lolita, the charming 13th Street bistro where Mexican flavors are an inspiration rather than an exercise in authenticity.

Not to say there aren't sauces and ingredients here that are faithful to tradition. Chef and co-owner Marcie Turney, known for her neo-Mediterranean flavors at Audrey Claire and Valanni, has worked hard to learn and use the labor-intensive techniques of proper Mexican cooking. The velvety soft, steaming-hot tortillas she makes for the carnitas and queso fundido, for example, are superb.

But when you tuck into a plate of tequila-cured smoked salmon draped over malanga chips with jalape��rema and crunchy heirloom radish salad, it's clear that Lolita is more contemporary BYO than barrio taqueria.

There's nothing wrong with that, especially when it's BYOT (as in tequila), and the margarita punch is as lip-smackingly fresh as Lolita's virgin mix. And with a healthy pour of good tequila (we indulged in Patron Silver), this stuff is as dangerously drinkable as a Scorpion Bowl.

The servers are welcoming and attentive, well-versed on the food, and impressively attuned to customers' special needs (such as my guest's allergy to nuts).

The space is just right, too, an angular glass storefront that opens onto a slender room done in a simple but urbane style: exposed brick walls and steel air ducts, flickering votive candles, arty photos, and a fire-red mosaic of glass tile fronting the open kitchen.

Plenty of chic accents, from the sleek shoehorn-shaped margarita stirrers to the hot-rolled steel mirrors over the banquettes, have been borrowed from Open House, the home store Turney owns with her partner and Lolita co-owner, Valerie Safran.

Lolita is considerably more mellow than the fiestalike frenzy shaking down the street at flashy El Vez, and it's simply a pleasant place to dine. The food is also lower-key than that of its neighbor and rival, more straightforward - sometimes blander, but usually interesting enough to be worth a visit.

Lolita's guacamole is fresh and simple, a cool green cream topped with jicama slaw for crunch. The butternut squash soup creamed with coconut milk is perfectly seasoned and textured with chunks of sweet calabaza and crunchy pumpkin seeds.

The queso fundido was impossible to resist. I'm a goner for crocks of bubbling Oaxaca cheese laced with roasted peppers and cuminy chorizo - though I'm not sure what those tufts of microgreens were doing on such a lusty, primal dish.

If Turney has a weakness, it's that penchant for reflexively piling heaps of boutique produce on every plate. It's one thing to highlight good local ingredients, but they're cheapened when used like parsley. And the steady shower of tiny leaves and sprouts and shaved organic roots detracts from the earthy flavors the kitchen so painstakingly creates.

The salmon tostaditas are an exception, their ideal balance of fresh flavors tumbling over malanga chips in perfect harmony. But in other dishes, the surfeit of ingredients was a distraction. I loved the depth of the rustic red mole-sauced chicken-and-corn stew in the tamal. But freshly ground masa, the essential element of any tamal, was virtually absent, as was the flavor of the coveted huitlacoche.

The Veracruz-style red snapper had other issues (including serious oversalting). But adding white beans, green beans and asparagus - and omitting the usual tomatoes - seemed a gratuitous deviation from a simple classic that is a bellwether for any Mexican menu. The carnitas stewed with orange and cinnamon was on the sweet side, but at least it was in the right hemisphere.

The kitchen seemed more at ease with dishes that required a less specific preparation. The halibut was excellent, posed over a brothy hash of cubed chayote squash, tender clams, and spicy chorizo. The chile-rubbed pork loin should have been a notch spicier, but I liked its musky, cinnamon-tinged sauce and garnish of shaved corn piqued with anchos and cotija cheese.

Satisfying enchiladas verdes filled with shiitakes and Lancaster jack cheese came topped with bright green tomatillo salsa and succulent grilled shrimp singed with smoky chipotle marinade.

The barbacoa of roasted lamb flavored with a spice box of Mexican aromatics was one classic Turney nailed. A bonus of grilled pasilla-rubbed lamb loin and hazelnut-huitlacoche stuffing added a surprising update to the dish.

There were similar tasteful tweaks at dessert. The milk-soaked tres leches cake alongside creamy chocolate pot de creme was a treat. The bread pudding with apples, walnuts and rum-splashed plantains was a smidge too moist, but irresistible.

It was the cheesecake, though, that I'll remember best. The creamy wedge was scattered with pecans, streaked with goat's milk cajeta caramel, and set in a chocolate cookie crust that left a warming surprise. When I licked my lips, they tingled with a whisper of ancho chile.

Contact restaurant critic Craig LaBan at 215-854-2682 or claban@phillynews.com. Read his recent work at http://go.philly.com/craiglaban.