Gaucho beef: Grilled and sliced sirloin served with seasoned rice.

Rare is the diner who would tolerate a restaurant's repeated openings and closings. It is challenging enough to please some of the people all of the time when the doors are ajar, but it is nearly impossible to do so when they are periodically and unpredictably closed.

The fact that La Tortilla Feliz has any customers, let alone scores of contented ones, is a testament to its charms. This Central and South American eatery, located in Tremont, has closed and reopened for business twice in the past six years. But it manages to improve with each revival.

La Tortilla Feliz has never been perfect. In the early days, the restaurant exasperated diners with irregular hours and lackluster service. Fans were willing to overlook these faults, however, in light of the restaurant's laudable employee-owned arrangement and its intriguing mishmash of Latin-American comfort foods. An eight-month retooling in 2002 gave the restaurant a polished new look and more conventional business model. Additionally, both the menu and the service received significant upgrades, proof that the ends justified the means.

The most recent shuttering begat changes that are less noticeable, but also more shrewd. Keen to current culinary trends, the restaurant has reworked its appetizer listing into an expanded "small plate" selection. Add-ons in the form of side dishes are popping up on seemingly every menu, and La Tortilla Feliz is piling on with its catalogue of a dozen "extras." A revamped lounge area, outfitted with armchairs, sofas and low-slung tables, provides a cushy new roost for flighty nibblers and tipplers.

La Tortilla Feliz is not a Mexican restaurant, and that fact begins to sink in with the arrival of the complimentary tamalitos, diminutive meatless tamales. These tasty half-moons of fried cornmeal dough are served with a thin, smoky bean dip. Made with very ripe and very rich avocados, the guacamole ($4) pretty much sets the standard in the chip-and-dip department, especially when scooped with fresh-fried tortillas. Good, too, are the stuffed avocados ($7), hollowed-out avocado skins filled with a chunky salsa of shrimp, avocado, tomato and cilantro.

In the reina pepiada ($3), plump cornmeal pancakes are baked up crisp, sliced open like hamburger buns, and filled with a cool chicken and avocado salad. The perfect union of warm and cold, crunchy and creamy, yin and yang, arepas are the Venezuelan version of sliders.

Because Tortilla Feliz deals in unfamiliar Honduran, Venezuelan, Salvadoran and Cuban foodstuffs, the new menu wisely added a glossary of terms. Forget what the heck a plantain is? No sweat; the lexicon reminds us that it is the starchy cousin of the banana eaten only when cooked. They appear as faintly sweet fried patties beneath a flank of moist pan-roasted salmon ($16). Topped with a refreshing coconut-chive cream sauce, the dish is like a tropical breeze amid an urban jungle.

Among the finest dishes I've eaten all year, the chile-rubbed, adobo-sauced pork chop ($15) is succulent, flavorful and ringed with enough fat to keep things fun. Served on the bone, the chop is sided by coconut-scented black beans and rice. Like most dishes at Tortilla, this one has enough spice to awaken the tongue without igniting it. Less exciting, but a good bet for the less adventurous, the gaucho beef ($16) is a deftly grilled and sliced sirloin steak served with seasoned white rice.

A classic Cuban dish of long-simmered flank steak, ropa vieja ($16) falls apart like tattered "old clothes." This is perhaps the most aggressively spiced dish on the menu, which might explain why it is paired not with warm rice but with a fresh chickpea and tomato salad. Personally, I'd prefer a short stack of those killer corn arepas.

For dessert, diners have their choice of sweet caramel flan ($5), a sampling of seasonal fruit sorbets ($6) or a tumbler of fine aged tequila. Whereas other Latin restaurants strive to achieve notoriety through mile-long tequila lists, La Tortilla Feliz focuses on quality over quantity. The well-chosen sampling features just enough blancos, reposados and anejos to satisfy every taste.

The above is not to imply that this "happy tortilla" hasn't a few issues it can improve. Service can still be erratic, rushed or noticeably absent-minded. And that newly configured lounge area, while a nifty move, looks as if it was furnished with a quick run to Unique Thrift. Current hours are less than conventional, with no lunches, and dinner served only Wednesday through Saturday.

But longtime manager Christina Smith assures us that further tweaks are around the bend. Let's just pray the restaurant need not close again to accomplish them.

La Tortilla Feliz: 2661 W. 14th St., 216.241.8385. Hours: 4:30 to 11 p.m. Wed. through Sat.