Chocolate was oozing from the molino (“mill”) at el Mercado de Abastos, the central market in the city of Oaxaca—thick rivers of deep brown chocolate. I was there with Susana Trilling, who owns the local cooking school and bed-and-breakfast Seasons of My Heart, and a fellow student from the school. Before the chocolatemaker ground the toasted cacao beans with cinnamon, we had pinched them out of their shells on a flat surface, and he had blown lightly on them to clear away the shells; the beans were bitter, with a lingering aftertaste. The speed of the mill’s turning stones had then transformed them into a thick goo about the consistency of peanut butter. Next the miller mixed in sugar by hand and ran the whole concoction through a second mill, from which it emerged as a more uniform, pasty chocolate. We took a big lump of the finished product back to Seasons of My Heart, in the Etla Valley outside the city, where we shaped it into bars that could be used in numerous ways, from hot chocolate drinks to some of the complex sauces called moles.

And in Oaxaca moles rule, according to the 47-year-old Trilling, who is widely considered a leading authority on the cuisine of that southern Mexican state. She is also a popular cooking instructor who gives classes all over the world, including Texas; from April 1 through 6 she’ll be teaching at the Central Markets in Houston, Plano, Fort Worth, San Antonio, and Austin.

Though she was born and raised in Philadelphia, her maternal grandparents—who hailed from Tampico and Durango, Mexico—lived in San Antonio. (She still has relatives to visit there when she comes through Texas to teach cooking classes.) I met Trilling in the mid-seventies, when she was cheffing first at Austin’s Sweetish Hill bakery and then at Fonda San Miguel, a restaurant specializing in the cuisines of the Mexican interior.

After leaving Austin in 1978, Trilling ran restaurants and a catering company in New York City. She first visited Oaxaca (Wah-hah-kah) in 1983, when she joined friends for a three-week “vacation” doing volunteer work at a coastal orphanage for disabled children. She left New York in 1986 to take a break from the restaurant business and travel the world, spending much of her time in Australia and Thailand. In 1988 she returned to Oaxaca to volunteer for another six months at the orphanage. Then she moved in with Eric Ulrich, a Dutch farmer, at Rancho Aurora, where he grows tomatoes, corn, and beans. They have four sons, two of them adopted from the orphanage.

Though she was already cooking her own Thai-Mex fusion dishes, she began learning about the distinctly local cuisine from neighbors as she picked up the language. Soon she was holding afternoon baking classes to teach Oaxacan women how to make everything from pizza to brownies; those classes evolved into international ones that touched on a different cuisine each week. When guests staying at the ranch’s bed-and-breakfast started asking for Mexican cooking lessons, Trilling instituted weekend classes taught in English. In 1999 she published a cookbook and hosted a PBS series—both called Seasons of My Heart: A Culinary Journey Through Oaxaca, Mexico. (She will be signing her cookbook at the Texas Hill Country Wine and Food Festival—at the Salt Lick Pavilion in Driftwood, near Austin—on April 7.) Since then, her classes have grown so quickly that in October 2000 she moved them from the kitchen in her home to a new, domed school on the ranch. She now teaches classes that run from a day to a week and offers a ten-day culinary tour of Oaxaca. Like the cookbook and television series, the classes focus on traditional Oaxacan cuisine and methods while including modern variations on them. For instance, Trilling uses traditional utensils like the comal(a flat, round griddle of unglazed clay that is placed over an open fire) but shows how to get a similar effect with a griddle or cast-iron skillet.

The cooking of Oaxaca is rapidly becoming the Mexican cuisine of choice among foodies who have made the leap from distinguishing between Tex-Mex and interior Mexican dishes to recognizing the culinary differences of the country’s various regions. This is a diverse, labor-intensive cuisine of fresh fruits and vegetables and complicated sauces. Rooted more in ancient tradition than most Mexican cuisines, it is considered special even within Mexico. “Because this is an agricultural area, the produce is picked ripe and has much more flavor,” Trilling says. “Tradition dictates the toasting, roasting, and frying of ingredients to bring out their flavors even more.”

Trilling divides Oaxacan cuisine into seven regions, from the diverse foods of the mountains-and-coast microclimates of the northwest Mixteca to the fresh, smoked, salted, and dried seafood and game of the southeast Isthmus of Tehuantepec, with all of them melding together in the city of Oaxaca. The three foods that all seven regions share are black beans, corn, and squash; the traditional ceremonial dish Ma’ach, eaten by law every August 1 in the village of Tamazulapan Mixe to ward off hunger in the last month before the harvest, is one of the few that includes all three.

Moles, which often contain more than 25 ingredients and can take two days to make from scratch, combine Mexico’s old (dried chiles, tomatoes, and seeds) and new (European spices) gastronomic worlds. In nearby Zaachila, mole pastes are made by frying all but three ingredients until they are dry; when ready for use, the paste is reconstituted by adding the remaining trio of ingredients—tomatoes, tomatillos, and broth—which cuts the cooking time down to as little as an hour and a half. Though Trilling believes that moles probably originated around the same time in several regions of Mexico, they are most closely associated with the state of Puebla. Seven types are found in Oaxaca, each with as many variations as there are families. They range from the mild verde (“green”) to the sweet, fruity manchamanteles (“tablecloth stainer”) to the negro (which contains five chiles and is eaten mainly during Day of the Dead celebrations) and the brick-red coloradito (which is used as a sauce for enchiladas or chicken).

Beyond the food, Trilling considers two concepts central to Oaxacan cooking. The first, guelaguetza, which means “reciprocal giving and taking,” refers to how rural farmers distribute their crops among one another and is also the name of the state’s biggest tourist event. At this annual July festival, the various indigenous groups converge on the city of Oaxaca to dance, play music, and exchange gifts, art, and crafts. Trilling’s other key concept is embodied in the word aprovechar, which means “to take advantage of.” While tortillas cook on the comal, for example, vegetables are roasted directly on the coals under it to take advantage of that heat; when the vegetables have cooled and been peeled, their flavors are stronger than they would be if they had been boiled or used raw. At the end of a meal, everyone at the table says “Buen provecho“—meaning, roughly, “take advantage of this food to improve your health.”

Oaxaca is an agricultural state with sixteen indigenous groups, each with its own dress, language, and traditions. The beauty of Trilling’s approach to teaching is that she gives culture as much importance as cooking, and there’s considerable travel involved in the longer courses. One morning during my five-day spring class, we toured the mammoth, ghostly Zapotec ruins of Monte Albán, outside the city of Oaxaca, where some 16,500 people lived at its peak, between A.D. 300 and A.D. 500. From there we drove on to Santa Maria el Tule, where the market stands in the shadow of an ahuehuete (a relative of the bald cypress) that is reputedly the oldest and largest tree in the world. At a fonda (diner) in the market, we snacked on empanadas de mole amarillo con pollo (pies filled with chicken in a yellow mole thickened with masa, or cornmeal). Next came the market in Tlacolula, where the specialty is unglazed red pottery from nearby San Marcos Tlapazola and the food in the stalls includes an especially flavorful sweet potato with a red skin. At Trilling’s favorite fonda here, we happily slurped a soup made with barbacoa de chivo, a goat that is cooked in the ground; lime and chopped cabbage, cilantro, and onion were served on the side, to be added at will. Then our van began climbing into the Sierra Mixe (named for the people who inhabit this eastern part of the Sierra Madres). We grew more and more silent as we ascended and took in humbling views of mountain peak against mountain peak, each a little higher than the one before. At the market in Ayutla, where the meat and fish were dried because it takes so long to transport them there, mustard greens simmered in ollas (clay pots) until ready to be eaten with salsa. Many of the women wore the blue and white cowgirl outfits of the nearby village of Santa Maria. Ten minutes farther on, in Tamazulapan Mixe, we were greeted by the smell of wild green onions and wild mountain apples. After we stopped to rest in the plaza of the municipal palace, where we watched boys playing soccer and men playing volleyball as local bandas competed for the right to represent the town at a national music festival, cheerful day-drinkers implored us to drink from their small bowls of potent pulque. Unfortunately, the mountains had become socked in with fog, and we couldn’t continue on to Totontepec, where the largest corn in the world is grown, its stalks averaging sixteen feet high and its ears sixteen inches long. On other days we visited bread-, cheese-, and tortillamakers and an elderly woman who showed us how to create frothy chocolate de agua (hot chocolate made with water) and tortillas embarradas, large, crispy tortillas called tlayudas that are spread with a bean-and-chile paste and usually eaten as a mid-morning or late-night snack.

But we also got a lot of cooking done ourselves. Trilling—a perpetually cheerful and often self-mocking teacher with a gift for making students feel they are learning even when they mess up—doesn’t like to give demonstrations; instead, students roll up their sleeves and, supervised by Trilling and her assistants, cook their own dinner. One morning we went to Trilling’s local market in Etla, which is known for its three cow’s-milk cheeses, to shop for ingredients. Later, fortifying ourselves by sipping beer and delicious lemon or hibiscus aguas frescas (flavored waters), we each fixed one dish for the evening’s meal. Saundra, an orthodontist and former University of Michigan professor, prepared arroz con chepil (rice flavored with a delicate pre-Hispanic herb that grows wild in the rainy season and has an intensely “green” flavor, like parsley or watercress). Her daughter Melanie made ensalada de piña, jicama, y aguacate (juicy pineapple-jicama-and-avocado salad), with the crunch of jicama and toasted pecans setting off the softness of the other ingredients. Olga, a retired New York City schoolteacher, and Pauline, a Toronto magazine editor, had the biggest challenge in chichilo oaxaqueño, the most unusual of the seven moles. Traditionally served over pork or beef, it derives its remarkable taste largely from poached chayotes (green, pear-shaped squash) and string beans, burnt tortillas, and the blackened seeds of two Oaxacan chiles. When the garnishes of lime, roasted green chile, and onion were added, the flavors really came alive. I fixed caldo de gato, clear beef (not cat) broth with summer vegetables; it was rather bland until we added a salsa of chile, tomatillo, and garlic. For dessert we enjoyed a pay de queso (farmer’s cheese pie) with guava that had been made by Leigh, who was in the music business in Detroit, and Joan, Pauline’s mother. There were no kitchen disasters, and that night I slept well on a full stomach.

Only Leigh and I were left on the day we visited the central market in Oaxaca and watched chocolate being made. We also wandered through sections full of stalls with incredibly fresh fruits and vegetables and a huge area of unfamiliar regional chiles. One corner of the market deals exclusively in dried gusanos (“worms”) and chapulines (“grasshoppers”), both considered delicacies; superstition holds that anyone who eats chapulines in Oaxaca is certain to return. In the amazing seafood section, we bought three gleaming red snappers weighing a total of two kilograms (around four and a half pounds) for about $13.25.

After returning to Rancho Aurora, the three of us produced an explosive coctel de camarón (“shrimp cocktail”), a hearty arroz a la jardinera del Restaurante Yalile (a rice dish with potatoes, carrots, and other vegetables that is named for the Tuxtepec restaurant where Trilling first learned it), and a refreshing ensalada de botana (an appetizer salad of lettuce, tomato, radish, avocado, green onion, and cheese in a jalapeño dressing). But the real treats were pescado empapelado al diablo and ante de mango. For the former, one of the snappers was topped with a devilish hot sauce, wrapped in banana leaves, and placed in an aluminum foil tent atop a hot comal. Steamed quickly in the foil, it was unbelievably moist and tasted out of this world. The ante de mango, an intensely flavorful mango pudding that requires no cooking, is unlike any other dessert I can think of. It has become a favorite at my house, but then I have yet to meet a Oaxacan dish I don’t like.

Seasons of My Heart, phone and fax 011 52 95151 87726 or 011 52 95150 80044; ; seasonsofmyheart.com. One-day class $75, 4 days $850, 7 days $1,695, 10-day culinary tour $2,300; prices include everything but plane fare. Two students lodge at Rancho Aurora’s bed-and-breakfast, the others in town at Casa Colonial and Posada de Chencho. A van provides free transportation to and from the hotels as well as the airport.