Just the idea of Mexican food can bring out the worst in New York diners and restaurant owners alike: the former tend to be more interested in a tequila-fueled good time than what's on the plate, and the latter have been known to pack 'em in and overcharge 'em, unless, of course, they're keeping out the hordes with an aggressive bouncer and a velvet rope.

Not so with the low-key Papatzul, just opened on Grand Street in SoHo, in the space that housed La Jumelle. The beautiful old oak bar is still there, and behind it is a bartender so friendly that we decide to have our entire meal perched in front of him. The dining room doesn't seem very warm, somehow, and there we might be serenaded by the band, the members of which inform one of us, in Spanish, that they are decidedly not a mariachi band, but a serious group of performers. This distinction is one Papatzul itself faces, and at times, it teeters on the border: fun and slightly campy vs. serious Mexican.

People like to judge Mexican restaurants by their guacamole and margaritas. To be honest, I don't think there's that much difference, in such simple concoctions, between good guacamoles/margaritas made with fresh ingredients, except that each has its own style. Papatzul's guacamole is bright and citrusy, flecked with dark green minced chili peppers when ordered medium spicy. The margaritas have the bite of fresh lime without too much sugar. The menu is limited, but many of the items on it are lighter, authentic Mexican fare. In the ensalada palmito, each element shines - the briny pickled hearts of palm hit just the right note against the sweet slices of pear. The chilapitas de camarones - tortilla cups of shrimp, mango and jicama - have the same bright citrus punch of the guacamole but are too simplistic to be particularly interesting. The thick tomato sopa de tortilla could use some more spice too. We allow ourselves a tortilla pie - guilty filler Mexican food, basically, but very satisfying and tasty all the same.

A friend who has spent a lot of time in Mexico steers us toward the chile poblano relleno de calabza alamendras, a poblano chili stuffed with butternut squash and served over a sauce of tomato, currants and almonds. It's very authentic, she says, and perfect for November, when chilies are at their best. I don't know much about the seasonality of chilies, but the combination of the smoky, spicy baked chili and sweet butternut squash has a certain mystery that seems quintessentially Mexican. Just as, with a good mole, you wonder how any one thing can be chocolately but not at all sweet, earthy yet burningly spicy all at the same time, the chile poblano tastes much more complex than it can possibly be without any added spices, and yet there don't seem to be any spices added. The paradox strikes me at levels both sensual and cerebral, but if you asked anyone more familiar with the territory of Mexican cuisine, they would tell you that Papatzul's food tastes decidedly homey.

55 Grand Street, between West Broadway and Wooster Street