In our continuous pursuit of the perfect sandwich, we tend to focus on the fixings and just take the bread for what it is: a frame. But when we stepped up to the counter to order a roasted-eggplant sandwich at Mariposa Bakery, we were faced with a question that made us realize we’ve been going about our quest all wrong: "Would you like that on seedy, white, potato, or a pretzel?" On a pretzel?! Yes, all it took was a pop into Mariposa, a striking, cozy alcove on the fringe of Central Square, to turn our hunt on its head. Um, a pretzel, please.

This new eatery has lime-green walls, black tables and chairs, funky light fixtures, and exposed-brick walls, a décor rather like SoHo-artist’s-loft-meets-European-luncheonette. Just a warning: the cookies, muffins, scones, and other puffy pastries that sit prettily along the counter may pose a threat to your best lunch intentions. Oatmeal-nectarine scones ($1.95) and raspberry-streusel muffins ($1.65) are just two of the sweet bites owner/chef Suzanne Mermelstein whips up early each morning. But did you really expect oatmeal-raisin cookies and blueberry muffins from someone whose résumé includes a three-and-a-half-year stint at Rialto?

We wonder if that bistro’s Mediterranean cuisine inspired her intriguing twists on basic deli sandwiches. The tuna sandwich ($6.75), for one, is infused with shaved fennel and lemon-herbal vinaigrette and garnished with ruffles of arugula. The avocado ($6.75) is layered between bread slices with radishes, sunflower seeds, and a creamy goat-cheese concoction. Oh yeah, about that roasted eggplant — the pretzel roll is like sweet-challah-meets ... well, a pretzel. The sweetness nicely offsets the saltiness of the roasted cherry tomato and eggplant. Plus, it reminded us that it was just about time for another dessert.

Mariposa Bakery, located at 424 Mass Ave, in Cambridge, serves food Monday through Saturday, from 7 a.m. to 7 p.m. Call (617) 876-6500.