8009 Norfolk Ave., Bethesda 654-4443 Hours: 11 a.m. to 10 p.m. Monday through Thursday, 11 a.m. to 11 p.m. Friday and Saturday, 5 to 10 p.m. Sunday. Prices: Most dinner entrees $8 to $14. Cards: American Express, MasterCard, Visa.

So many Mexican restaurants are so awful that it's nice to have Tia Queta around just as a reminder of how good Mexican food can be.

This place is still serving up a broad array of authentic dishes -- far broader than the typical, repetitive list of corn-cheese-bean permutations that ordinarily pass as Mexican food. And those dishes are consistently well prepared. In fact, consistency is the keynote here: In its sixth year, Tia Queta seems to be doing an even better job than when it opened. People seem to know it, too. The place is packed on weekends, and even the week nights can be noisily busy. Despite all the hustle and bustle, the servers are quick, efficient and accommodating, and they don't rush you.

Among the appetizers, the mussels have been flawless lately, plump and sweet, in a lively tomato, olive oil, onion, pepper and garlic sauce. If you're a ceviche fan, don't miss Tia Queta's rendition, with big pieces of marinated fish, tender and firm-textured, in a sauce with olives, chile pepper and cilantro that strikes a perfect balance between hot and citrus flavors. The stuffed avocado is lovely, too.

Sidestep the queso fundido, though, a melted cheese appetizer that's heavy, salty-tasting and oily. But don't sidestep the soups. The tortilla soup is a rich, robust gem with chunky tomato, avocado and cheese. The garlic soup is good but less showy. The black bean soup has been properly flavorful, but on our last visit it was so mushy it resembled a lumpy gravy.

One of the best entrees in the house remains puerco yucateco, tender pork chunks in a delightfully tart sauce flavored with vinegar and bitter orange. (It's also available with an unremarkable flounder, but stick with the pork version.)

Another very good meat dish is a Mexican version of barbecue called carne enchilada, a huge portion of thinly sliced pork, marinated in vinegar and spices for tenderness, then charcoal grilled and served in a bit of tomato-based sauce.

Still another first-class dish is pipian rojo, a butterflied chicken breast that's remarkably moist and tender, in a subtle, complex sauce with tomatoes, pumpkin seeds and coriander. (Have patience with this one; it grows on you.)

There's also chicken, with the traditional chocolate-based mole sauce. Although the sauce has a nice tartness to cut its cloying quality, this is still a very rich dish that most people will find better for sharing than solo eating. Shrimp Tia Queta has been remarkably good, big and fresh tasting, in a robust, chunky sauce with tomatoes, sweet peppers, olives and garlic.

There are the standard Mexican items, too, and they bear no resemblance to the glop served in many Mexican restaurants. The enchiladas, for example, aren't engulfed in sauce; they have real texture and tooth to them; their tortilla wrappers are chewy and crisp around the edges, and their fillings distinct.

There are a couple of dynamite desserts: an ethereal, shimmery flan, and caramel-sauced crepes that are simple but irresistible.