I ONCE heard a comedian tell a joke about Mexican food in which he pretended to be a jaded waiter at a Mexican restaurant describing various dishes to a white bread Midwestern diner who'd never had the food before. The mock dialogue went something like this:

"What's a tostada?"

"It's a tortilla with cheese and meat."

"What's a taco?"

"It's a tortilla with cheese and meat."

"What's an enchilada?"

"It's basically another riff on the tortilla, cheese and meat theme."

For many people, Mexican food is just a series of permutations on a few familiar ingredients, because most Mexican restaurants in America seem to be cooking off the same menu—an endless parade of burritos, tacos and enchiladas. Much harder to come by are restaurants that go beyond these familiar, often Americanized dishes and offer some of the diverse regional cuisines of Mexico. That's what makes El Tule restaurant in San Jose such a find.

Most of the menu is devoted to Mexican-American standards, but recently the 16-month-old restaurant introduced a separate menu that highlights specialties from the southern Mexican state of Oaxaca.

With its deep Zapotec and Mixtec indigenous roots, Oaxaca is the source of one of the most complex and delicious cuisines of Mexico. El Tule, which is named after a mammoth, 3,000-year-old cypress tree in Oaxaca—believed to be the world's largest living thing—only scratches the surface. But it's a start and a refreshing break from the same old rice and beans.

Esteban and Esmeralda Gonzalez own the restaurant and Esmeralda's mother, Guillermina Martinez, does the cooking. It's a bright and clean place that was sadly short on customers during my visits. This is a wrong that must be righted.

Esmeralda, who often had her 2 1/2-year-old son in tow while waiting on my table, is proud of her restaurant's food and is good at explaining some of the more unfamiliar dishes like the chapulines ($4.50). Chapulines are toasted grasshoppers seasoned with lime juice, salt and chiles. The insects are exponentially higher in protein than beef and have been consumed in Mexico for thousands of years. The little bugs are cleaned and washed before being cooked and have a nutty base of flavor that's all but obscured by the spicy, salty tang.

They're served in a little bowl and you eat them with your fingers, kind of like pretzels. Except they're bugs. They're less daunting than they sound and go really well with beer. Alas, they're not made in-house, but are still worth a try.

Mole is a catchall term that refers to any number of silky, complex sauces. Most common is the chocolaty mole poblano, but Oaxaca is famous for numerous versions such as yellow, green and red moles. El Tule serves a black mole Oaxaqueño that is one of the best I've ever had. The recipe comes from the owners' hometown in La Mixteca, Oaxaca.

The velvety sauce starts out with a light sweetness that gives way to pleasantly spicy and slightly bitter flavors and layers of complexity that come from the sauce's laundry list of ingredients. Draped over juicy chunks of chicken and served with fresh corn tortillas ($10.95), it's fantastic.

Tlayudas are a common snack in Oaxaca, often served on the streets of Oaxaca City by vendors at night. They look like big tostadas, but are a bit different. The tortilla is as thin and crisp as a papadum, those crackers you get at Indian restaurants. Unlike a tostada, the tortilla is baked instead of fried so it's quite light and topped with puréed black beans, shredded lettuce, sliced avocado and a choice of meats. I went for the tangy, thin slices of marinated pork ($11). This a great dish to share so order one for the table.

Molotes ($10.95) are another Oaxacan specialty, but they were less successful here. They look like little footballs or torpedoes made with thick masa dough that is stuffed with potatoes and chorizo, fried and then topped with puréed black beans, avocado sauce and sour cream. The flavors were good but the masa was too thick and hard and required some heavy sawing with my knife.

Better is the pollo en escabeche ($10.50), tangy and tender chunks of chicken marinated in white vinegar with green olives, onion, carrots and, potatoes.

The few non-Oaxacan dishes I tried were good, but not as interesting. Pozole is a pork and hominy stew made throughout Mexico. At El Tule ($8.99), it arrives in a clear, rather bland broth, but it's served with a bowl of thin, red salsa, chopped onions and limes on the side. Once doctored up, it was good, but still a little wan.

Esmeralda says the response to the restaurant's addition of Oaxacan dishes has been great and diners are driving in from San Francisco and Monterey. They plan to add more in the coming months. That's great news for Mexican food lovers ready to try something besides the same old tortillas, cheese and meat. I can't wait for more.