Way down in the far reaches of Sebastopol Road, next to a small market and a row of vacant spaces, tucked into an unassuming mixed-use storefront, there's the greatest Mexican dish you've never heard of.

Panuchos are a staple in the Yucatán region of Mexico, but in Sonoma County, there's only one place to get them, and that's at El Rinconcito Yucateco. They're divine. They begin with fried, handmade tortillas filled with black bean purée. Lettuce, tomato and avocado are sprinkled with lime and pickled red onions, and soft, seasoned chicken rounds it out with a grilled pepper on top.

Panuchos have been the area's best-kept secret since El Rinconcito Yucateco opened four months ago, but the word is getting out. What's more, the small family-run spot offers many other Yucatecan dishes, most of them exclusive to the modest, tile-floor restaurant space, and all of them delicious to those who've had their fill of the same old taqueria fare.

El Rinconcito Yucateco was opened in January by husband and wife Lupe Cazares and Carmen Castillo, and much like the handful of Michoacán-style restaurants dotting the taqueria landscape in town, it offers a new twist of fresh flavors and different styles of Mexican cuisine. In addition to panuchos, there's poc-chuc, a soft pork marinated in black pepper, lemon juice and orange juice; escabeche, a boiled chicken soup with onions marinated in orange juice and jalapeño peppers; salbutes, similar to panuchos but without beans; and perhaps the restaurant's signature dish, relleno negro, seasoned with a black spice paste made from an old family recipe.

"Come here, let me show you," says Cazares, smiling, leading me back to the kitchen. He pulls from the shelf a large plastic bag packed with a thick, dark substance—a mash of pepper, black corn and cake—that they call ricado negro. "It looks like black mole, but it's not quite black mole," he says. What it actually looks like is black tar heroin, and I can smell its deep, hyperactive aroma from six feet away. Castillo's mother makes ricado negro by hand in Mexico and sends it from her hometown in Yucatán to Sonoma County for use at El Rinconado Yucateco. It's a true Yucatán ingredient, made and sent from the source.

Cazares moved to Sonoma County from Michoacán in 1981 to join his brother. Since then, he's always worked in restaurants, waiting tables, cooking, bartending, dishwashing. At Las Parrillas in Cotati, where he worked for 14 years, he filled just about every role except owner. Then he met Castillo, at the time working as a hotel housekeeper to support her family who'd recently moved from Peto, Yucatán.

Peto is a small town founded in 1549, population 18,177, where people still mostly use pedicabs to get around. Castillo, her daughter Bianca and niece Giselle moved here, and Cazares and Castillo soon met, married and made ends meet for the family by selling banana-leaf tamales on the street in Roseland. Somewhere along the way, Castillo began delivering panuchos to select customers' houses, and they were such a success that it made sense to open a restaurant.

Though Cazares always loved to cook for the entire family back home in Michoacán, the couple noted the presence of several other Michoacán-style restaurants in the city already. Castillo had spent countless nights in the kitchen with her mother back in Peto, absorbing a long line of Yucatecan tradition. Cazares, too, was picking it up from her quickly, and the panuchos were selling well. It just made sense, "because here," Castillo says, "there's no Yucatán restaurant. We already have Michoacán style already. This one is new for Santa Rosa."

Yucatán-style cooking is significantly different than other variants of Mexican cooking, due to both topography and the ship trade. Long ago, the Yucatán peninsula was cut off from the rest of Mexico by tall mountains and bad roads, but its port was home to ships from France, New Orleans and Cuba. The area's cooking reflects this European hybrid. "It's very different," says Cazares. "In Yucatan, they also have Mayan spices. There's a spice called aichote—it's a little fruit that comes from a little tree. They pick it up and grind it. We use it a lot in the pork and chicken."

A clean example of the poc-chuc with aichote can be found in the tacos ($2 each), which use shredded cabbage instead of lettuce. Marinated for a full day, the pillowy pork is soft, with overtones of lime. A full plate of poc-chuc ($9.95) includes black bean purée, roasted red onions, cabbage, radish, avocado and roasted tomato. Another trademark Yucatecan dish is the sopes, made from a thick, handmade tortilla topped with beans, green and red sauce, onion, sour cream and grilled steak.

Most dishes on the menu run $6.95 to $9.95, with a full page of seafood—fried tilapia, sautéed prawns, ceviche tostadas and more—priced only slightly higher. Vegetarians can get the panuchos without chicken—still quite good—or substitute mashed potatoes in the taquitos and other dishes.

Inside, the setting is down-home. The family still wakes up early to sell tamales every morning at the gas station next to Foster's Freeze, on Sebastopol Road at 5am, and operations at the restaurant find Lupe and Carmen in the kitchen and Bianca and Giselle waiting tables. Since opening in January, business has been good, especially considering its distant location in a string of empty storefronts, a development built just before the Great Recession. From the outside, it's a blink-and-you'll-miss-it spot.

But inside, it's as authentic as it gets.

"A lot of people have come here from Yucatán, and most of those people work in American restaurants," says Cazares. "When they get off work, they come here. This kind of place, they love it."

El Rinconcito Yucateco, 3935 Sebastopol Road, Santa Rosa. 707.526.2720.

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