If the concept behind Mercadito – to neatly bridge the gulf between cheap Mexican and haute Mexican – seems particularly smart and well-founded, it could be that restaurateurship runs in the blood. Patricio Sandoval, who opened the restaurant in September, is the brother of Richard Sandoval, whose national empire of refined Mexican restaurants includes Maya on East 64th Street and Pampano in Midtown. The brothers come from an Acapulcan culinary dynasty, and both credit their grandmother as a primary inspiration. She should be proud.

The tiny East Village space (augmented last week by a larger dining room in the back) seats just 20 or so, at closely situated little tables where local couples literally rub elbows, and at a bar that offers a fine view of Mr. Sandoval at work in the kitchen as well as a bit more room to stretch out than the tables do. Rough-hewn wood and woven slats give the room a casually tropical feel. Servers, though harried, convey a hospitable warmth, although their sincere enthusiasm about particular menu favorites can occasionally verge on pushiness.

Despite the sociable atmosphere, it’s the food that really grabs attention, as lavish and clearly defined flavors make bite after bite gratifying. Mr. Sandoval conceives a meal here as a collection of sharing-friendly portions, providing everyone a welcome opportunity to try several different dishes. Tacos, the core of the menu, come three to an order; for parties not divisible by three, $2 adds an additional taco to the plate. Some dishes offered individually, such as the ceviches, can also be ordered in combination, three at a time.

Guacamole, the logical starter, comes in three varieties: traditional ($7.50), rich and studded with tomatoes; mango with chipotle ($8.50), which has a fruity, smoky intensity; and pineapple ($8.50), whose sugary edge is lifted by mint and tomatillo. Or, for $12, all three come to the table in a tiered rack, with not quite enough of the house’s fresh, crunchy tortilla chips. The desperately hungry may prefer to start with queso fundido ($8.50), the thick Mexican cheese fondue that here is sprinkled with either dark wild mushrooms or garlicky crumbled chorizo.

A choice of several ceviches ($8 each, or three for $18) offers elegant variations on a theme. These are served, Central American style, with rough-shaped house-made crackers, whose wheaty, salty taste give the fish a hearty abetment, despite their tendency to crumble. The ceviches’ piquant coolness will be refreshing when the weather gets hot; for now it’s just delicious. Dense little chunks of scallop form the substance of one; they are joined by sweet cubes of pickled watermelon in a light orange-habanero broth. In another ceviche, strawberry and habanero give rich striped bass an invigorating push; the smoked mahi mahi in a third is reminiscent of oily smoked sable, though a trio of citrus juices cuts the fat nicely.

As at many other taqueria, tacos here come in a number of varieties, each featuring a particular meat or fish; but Mercadito’s tacos bear Mr. Sandoval’s particular stamp. The hand sized folds, large enough for about three average bites, literally drip with intense flavor. Chicken pieces ($7) get a vivid rosemary marinade that the grill deepens and sweetens, and are accompanied in the tortillas by buttery grilled corn kernels. Hoja santa, the distinctive aromatic herb sometimes called pepper leaf, serves as the marinade for skirt steak ($7.50), which, in its tart salsa, makes one of the best tacos. Mercadito’s version of tacos al pastor, stuffed with grilled pepper-rubbed pork, sweet grilled pineapple, and faintly grassy arbol salsa, excels too, though the meat falls just slightly short of tender.

Seafood also makes a fine showing: Baja-style tacos ($8) feature a fried fish of the day with a dual crunch – first from the beer-batter shell around the fish, and then from the fresh purple cabbage slaw. Tacos de mariscos ($8.50) offer a melange of undersea treasures: little bay scal lops, octopus legs, and calamari rings, sweetly caramelized and with a tart dressing; these mariscos can also be had with baby spinach in salad form ($9). Shrimp get a taco of their own ($8.50),where they are drenched in a strong, red chipotle-garlic sauce.

Mercadito has a handful of offerings beyond the tacos. Cactus leaves ($9), breaded, stuffed with ricotta-like requeson cheese, and topped with roasted tomato salsa, are firm and flavorful; picadas ($9 for three) are thick tortillas served flat and topped, like the tacos, with chicken, steak, or pork. The lauded baked oysters ($9) don’t quite seem to unify their sea and land components successfully; the briny taste of the soft oyster meat struggles against its earthy topping of melted Manchego cheese and bits of chorizo.

Pumpkin flan’s powerful flavors of caramel, fruit, and spice, and topping of cinnamon cream, make it an out-and-out favorite ($7),with easily twice the flavor of the other desserts. A sampler of three desserts can be had, including chocolate flan and rice pudding, but three flans would be a better choice.

The house margaritas, made with lissome, fruity El Jimador silver tequila, are reason enough to visit the restaurant. They graduate from a classic lime version ($6) to fancy, delicious cocktails with more than a hint of hot pepper: one contains creamy jicama juice and powerful chipotle ($7), and another is made with habanero pepper as well as three citrus juices. In the particularly brilliant margarita de pepino ($7), triple sec brings out the shy, melony sweetness of cucumber juice, while chile de arbol’s throaty burn warms the gut and the spirit.

Sadly, the pleasurable saturation of the palate that these spicy drinks kindle mates in felicitously with complex food; the nuances of the cooking are better appreciated in the company of Mexican beer ($5), like full-bodied Negra Modelo, or one of the restaurant’s affordable wines. The menu lists two Mexican wines, a smooth, light barbera from Baja’s Santo Tomas ($7/$25), and L.A. Cetto’s dry chenin blanc ($6/$20); both are nicely balanced and complement the food excellently. The list also offers a number of Chilean, Argentinean, and Spanish wines, as well as over 50 fine tequilas.

Patricio Sandoval’s creative, delicious take on Mexican food is reminiscent of his brother’s upscale restaurants; but the simpler preparations, casual feel, and moderate prices appeal to a wide swath of neighborhood denizens. It’s a winning best-of-both-worlds formula, and it should take the restaurant far.

Mercadito, 179 Avenue B, 212-529-6490.