South University Ave. is decidedly student territory. But last month my husband and I joined the throng of youngsters scurrying along South U’s sidewalks.

We were prompted by a recent Marketplace Changes tidbit. Adam Lowenstein and Justin Herrick, owners of Good Time Charley’s, have transformed its upper-story sister restaurant, the former BTB Cantina, into Cantina Taqueria & Tequila Bar–a lunch and dinner taco place that morphs into a dance club after 10 p.m.

Perched above the sidewalk, with a stairway that seems more barrier than invitation, the second-floor location thwarts walk-in traffic. To offset that limitation, Lowenstein and Herrick hope to promote destination dining with higher-quality options that appeal to townies living in the nearby neighborhoods but that don’t alienate students’ financial sensibilities. They brought in a consulting chef–Magdiale Wolmark, who recently moved to town from Ohio–to upgrade the taco bar concept with fresh local ingredients, imaginatively rendered.

We had two lunches at Cantina, each time sitting along the expansive windows overlooking South U. Exposed to the daylight streaming in, the space, while smartly redone by Synecdoche Design Studio, still has, around its edges, the slightly tired feel of a late-night bar too early awakened. But my husband loved being above the fray, looking at the panoramic view of students in motion–the driving force, as he put it, behind Ann Arbor’s engine.

I wondered if late nights explained the friendly but less than stellar service of the woman behind the order counter, who also delivered the food after we had gathered our drinks and seated ourselves. At our second lunch we provided a little prompting, and she managed better.

On that initial visit we ordered each of the seven soft tacos listed. They came to the table overstuffed and handsomely tricked out, each graced with individually conceived garnishes–pickled radishes on the carnitas, shoestring fries on the chorizo, plantains on the mushroom. Favorites included the carnitas (braised pork), along with the other pork option–smoked belly outfitted with caramelized pineapple and onion. A charred romaine salad, Cantina’s take on a Caesar salad–tossed with Asiago cheese, diced tomatillos, and a lemony dressing–supplied our greens.

Next time we ventured beyond tacos. The “three sisters” version of the Cantina’s appetizer tostada was a delicious vegetarian dish layering black bean puree, sauteed corn, guacamole, and pickled vegetable relish on a toasted tortilla, its plate drizzled with a fruity, vinegary ancho sauce. In the future, I might order two tostadas as my lunch, with or without the optional meat. A special quesadilla with pepita (toasted pumpkin seed) pesto and tamarind-glazed onions was hearty and satisfyingly gooey. Pickled vegetables and another dulcet-tangy dressing punctuated the chopped salad. Chef Wolmark’s signature might be a sweet-tart tooth; all the pickled garnishes and salsas in the help-yourself salsa bar and on the menu offset sharp and/or fiery flavors with sweet and/or fruity ones.

Despite a mix of undergrad and graduate students, U-M faculty and staff, and other folks, at neither lunch did the Cantina fill up. Wondering how the nighttime vibe compared, we ventured to South U late one Monday evening only to find it closed. (I had misread the hours on the door.) I wasn’t willing to go home to make dinner–it was already 9 p.m.–so we strolled into Good Time Charley’s. It was a friendly, but truly fish-out-of-water, experience.

The fish tacos eventually put before me were delicious and my husband’s vegetarian burger fine. But the real wonders were the list of 131 suggestively named shooters–who knew there were so many ways to drink alcoholic sugar?–and the neighboring table that kept expanding, like a brushfire, by twos and fours, into a party of forty-and-still-growing merry college kids. Our waitress, alert and efficient, had us watered and fed, with check in hand, before the spreading mob could consume us completely.

Several nights later we finally sat down at a Cantina booth. The place was hopping, mostly with students but with a few parents sprinkled in; and this time a small battalion of servers was on hand to wait tableside. I ordered a margarita draft soda–house-made carbonated margarita on tap, only $5!–and my husband asked for a martini. “Why did you order a martini?” I asked after the waitress left. “They have a full bar,” he argued. “Yes, well, sort of, but she wasn’t even sure what gins they have. I don’t think it’s a usual order.”

Our waitress quickly returned to report they were sadly out of the draft soda–I really had been intrigued by that one–so I substituted a margarita rocks, and a perfectly fine cocktail it was, especially at $6. My husband, though, frowned after taking a sip of his $5 warm (!) martini. But, acknowledging it really wasn’t a martini place, he didn’t complain, instead stealing ice cubes out of my margarita to drop into his glass.

He had no complaints about his massive burrito, a kitchen-sink combo of pork, black beans, rice, guacamole, and cheese. All the components were fresh and tasty, a great base for his experiments with the array of salsas from the cold table. I stuck with a trio of my favorite tacos, finishing with an order of churros dipped in an addictive chocolate cajeta (goat’s milk caramel) sauce.

We had come to the restaurant late, but we didn’t stick around for the DJ to start. By the time we finished dinner the parents had left, along with most of those students who had been eating. The kids coming in now headed straight to the bar, waiting for the party to start. We’d had fun, but now our time was over, and we walked down the stairs to the street.

Cantina Taqueria & Tequila Bar

1140 South University

222-3715

cantinaannarbor.com

Lunch Mon.-Sat. 11 a.m.-2:30 p.m., dinner Tues.-Sat. 5-10 p.m. Closed Sun.

Dishes $3-$8.75

Service elevator only–ask at Good Time Charley’s.