In a city as big and bustling as Boston it can be difficult to keep secrets – especially juicy ones. Casa Romera is one of those secrets. Nestled in Public Alley 431 between Newbury Street and Commonwealth Avenue, the restaurant discretely serves up the city’s best authentic Mexican cuisine.

After turning the corner from Gloucester Street into the alley, it’s hard not to be distracted by the iron-grate, inner-workings on one of the Back Bay’s most popular streets. But it doesn’t take long to be drawn in by the curious glow of an over-sized tile door with a small sign overhead reading Casa Romero.

Owner and head chef Leo Romero said it was his dream to give customers the opportunity to “discover the heart of Mexico tucked away” in a Back Bay Boston alley.

“That is exactly what I had envisioned when I decorated the coffered door and walls of my restaurant with the bright Talavera tiles from Puebla, Mexico,” Romero said.

Inside, the underground space is festooned with Mexican art, tile work featuring warm colors covers tables and walls and heavy dark wood beams traverse the ceilings. The dining room is small and dimly lit, but bustles due to large groups of fourty-somethings who seem to make up the majority of the crowd on weekends.

The staff brings an authentic charm to the table, as well as extensive knowledge of the menu. With a slight language barrier and lack of English on the menu (translated descriptions are scarce, if available), ordering can be complicated. But, with a little customer patience, the staff can answer any question you might have.

Romero’s offers a vast, original selection of food from south of the border, the antithesis of Taco Bell’s kitschy value menu. Each selection is exciting and is separated into sections: seafood, meat and vegetarian.

Let alone the entree-picking an appetizer is a challenge since there are so many savory options.

Start by ordering the Chile Relleno, a Mexican classic featuring a stuffed poblano pepper bursting with gooey cheese, fried crispy and served in a not-so-spicy, yet, zesty chipotle tomato sauce. Or, perhaps, the chicken or shrimp flautas – crunchy handmade taquitos served with homemade Pico de Gallo salsa, heavily dolloped with sour cream and guacamole – will suit your stomach.

Much of the food is prepared with poblano peppers, which are big on flavor, but in contrast to the jalape