Donald Miller pulled a glass tube from a box behind the makeshift bar, prompting the sleeping Weimaraner at his feet to raise a suspicious eyelid.

"Ever tried wine straight from the barrel?" the American banker-turned-vintner asked as he used the tube to extract servings from a row of oak barrels while his dog resettled into slumber.

No, we replied, glasses extended. Truth is, neither had we ever sipped a robust cabernet before noon in the land of tequila and Tecate.

My husband, John, and I were in Mexico, in a pocket of fertile land on the Baja Peninsula, about 70 miles southeast of San Diego. The Guadalupe Valley has cultivated wine grapes since the 16th century, when Jesuit missionaries showed up with vine cuttings from Spain and an urge to plant. Russian immigrants took over the Jesuit mission in 1904 and continued to grow the same sweet, low-acid grapes best suited for brandy or inexpensive jug wine.

Only in the past decade have serious vintners arrived in Baja to prove that Mexican grapes can compete with the world's best vintages. Curiosity, more than a serious wine interest, drew us to the area last spring. We wanted to see how these small-scale winemakers were creating a respectable sipping destination just a few miles from the chaotic port town of Ensenada.

They're off to a good start, wine experts say, but they face climate challenges that will make it tough for their vineyards ever to match high-quality growing regions like Napa and Bordeaux. Most notably, the valley gets hit with bouts of high humidity during the late-summer harvest, explained Nick Dokoozlian, a viticulturist at the University of California at Davis.

"They're certainly trying to improve the quality by bringing in new technology and better plant materials," he said. "But it's not quite there yet."

No, it's not. Still, we sensed a serious attitude among the vintners during our visit, rather than the lighthearted party spirit that marked our previous wine-tasting jaunts to central and Northern California. We had well-equipped tasting rooms to ourselves. And we took the car on several dusty, traffic-free joy rides, where we spotted more field workers than camera-toting turistas.

Guadalupe has 11 wineries, about the same number Napa Valley had in the early 1960s. The two regions share a temperate climate and rolling landscapes, but the similarities end there -- at least for now. Napa's 280 wineries attracted more than 4.5 million visitors last year. On a good summer Saturday, locals estimate that Guadalupe gets a few dozen day-trippers from San Diego and the cruise-ship port town of Ensenada.

More hotels, restaurants and marketing campaigns are in the works, but visitors today can expect to find a pair of nondescript villages surrounded by vineyards, olive trees and boulder-strewn hills. The wineries are scattered around the towns of San Antonio de las Minas and Francisco Zarco off Mexico's Highway 3. Some offer personal tours that end with tastings of specialty blends in the winemaker's own kitchen. Others, like L.A. Cetto and Vinos Domecq, can accommodate busloads of visitors with hourly tours and picnic tables.

We spent the night at Adobe Guadalupe, a winery and inn owned by Miller and his wife, Tru. The Millers opened their sprawling whitewashed hacienda, the area's first and only hotel, in 2000 and had their first grape harvest the same year. The house and grounds are stunning, centered on a Mediterranean-style courtyard anchored by a large fountain. The six high-ceilinged guest rooms are decorated with Mexican tiles, wrought iron and bold colors.

As we unpacked our bags, we were greeted by the heady scent of eucalyptus and glasses of chilled 2000 Mogor-Badan chasselas, an elegantly dry white wine. "A reward for arriving," Tru told us.

When I booked our room, I also signed up for the inn's set-menu dinner for an extra $50 per person, which included a flight of local wines. Though the area has a handful of other restaurants, this turned out to be a good move. A lazy afternoon by the pool left us with little desire to brave another five-mile bumpy drive back to the main road.

We relished the four-course meal of cream of squash soup, garden salad, grilled swordfish and flaky apple tart as well as the accompanying wines (a crisp fume blanc from the nearby Chateau Camou winery and Gabriel, Adobe's own blend of cabernet sauvignon and merlot). It was the romantic setting, however, that left me with the evening's fondest memory: a grand dining room featuring a castle-worthy chandelier, fireplace and floor-to-ceiling views of the vineyards, spread across 60 acres.

We lingered long after the final pours of coffee and French cognac. On the way back to our room, we passed Donald Miller and some of his fellow vintners engaged in a boisterous kitchen game of dominoes.

The next morning, we joined Miller and a retired couple from San Diego on a tour of the premises. In the rectangular building where the barrels are stored, a young girl applied labels on bottles at a small desk, and the Millers' three gentle Weimaraners loped around with a self-importance that indicated they had been around long before the oak barrels.

While we swirled and spit cabernet tapped from the barrel, Miller told us that he and Tru have planted 10 varietals of grapes, including cabernet sauvignon, grenache, merlot and shiraz. Their first wines -- three red blends named after archangels, including the Gabriel we had sampled at dinner -- were released last year.

At the end of the tour, Miller offered us samples of Adobe's newest label, Uriel, a 2001 rose comprising five varietals. It was surprisingly dry and pleasant, and our fellow guests snapped up a $15 bottle to bring home. We shared their enthusiasm but held back on buying, since our tasting tour had just begun.

Our afternoon visits to Guadalupe's other wineries yielded more surprises that made our trip as much an adventure as a wine tour.

At Monte Xanic, a fortresslike facility surrounded by 160 acres of vineyards, assistant winemaker Jose Ochoa greeted us at the entrance and led us past aging oak barrels to the winery's mezzanine-level tasting room. At 15 years old, Monte Xanic (pronounced Sha-NEEK) is one of the older kids on Guadalupe's block. Its workers still handpick the grapes, which include cabernet sauvignon, cabernet franc, syrah, merlot and chenin blanc.

Ochoa offered us tastes of Monte Xanic's raspberry-laced cabernet sauvignon and a fruity 2000 chenin colombard, as well as Calixa, a lower-priced house line of medium-bodied chardonnays and cabernets. While we sipped, he told us that Mexican President Vicente Fox served Monte Xanic wines at his 2000 inaugural dinner. As the only guests in the echoing room, we felt a mild pressure to buy something and choose an $8 bottle of the chenin colombard and a slim tube of olive oil pressed from local groves (also $8).

Nearby, we toured the sleek facilities at Chateau Camou, then were taken to what can best be described as a tasting closet, which featured an overturned barrel topped with a wooden plank and bottles of Camou's chardonnays, zinfandels and fume blancs. Its signature wine is El Gran Vino Tinto ($18), a Bordeaux-style blend of cabernet sauvignon, cabernet franc and merlot that has picked up a slew of awards. We also liked El Gran Vino Blanco, which mixes sauvignon blanc with a touch of chenin blanc and chardonnay and sells for $12 a bottle.

(Both our guides spoke limited English, but they were clearly more comfortable speaking their native language. Visitors who don't understand basic Spanish may want to stick with tours of Adobe Guadalupe or the larger wineries.)

A few other small wineries worth noting are Mogor-Badan, known for its hard-to-find white chasselas, and Casa de Piedra, which is run by Montpellier-trained oenologist Hugo D'Acosta and is garnering attention from oenophiles for its complex red blend of tempranillo and cabernet sauvignon.

Our own impressions of the wines varied from sublime to so-so. Some, like Adobe Guadalupe's Uriel rose and Chateau Camou's Gran Vino Tinto, were revelations, in part because they were like nothing we had sampled in the past. Other blends were fine, though similar (and pricier) to what we could find at any well-stocked supermarket back home.

We ended our trip with visits to Guadalupe's two largest wineries: L.A. Cetto, around since 1928, and Vinos Domecq, a division of Spanish conglomerate Allied Domecq. These easy-to-spot wineries along Highway 3 felt more like Napa at its showiest, with their spacious tasting rooms and slick branding strategies. Still, they both offered whaddaya-know surprises that made us glad we stopped by.

At Domecq, a young man led us through a maze of dimly lit caves carved in the hillside and explained the Baja-style aging process: Keep the wine in oak barrels, then age it even longer in the bottle before releasing it. Afterward, we tried a 2000 red blend of zinfandel, cabernet sauvignon and caninan from the company's Calafia line. Our agreeable guide would have been happy to keep pouring from the dozen bottles lined up on the counter, but we were ready to move on.

Across the street at L.A. Cetto, we sampled a fume blanc in a tasting room that showcased everything from cold duck to a limited reserve nebbiolo. The woodsy white wine would have gone well with pate and crackers, but our food options were limited to refrigerated cheese and ice cream.

After the tasting, we explored the winery further, driving past a security kiosk and several huge fermentation vats. We found ourselves alone in a bullfighting ring perched on a hill above the winery, surrounded by bougainvillea and panoramic views of the valley's rocky hills and vineyards.

I tried to imagine what the addition of tennis courts, golf courses and luxury hotels -- what local business executives want to bring to Guadalupe Valley -- would do to the landscape. For that, all I had to do was think of Napa.

Laura Randall last wrote for Travel on California's Salton Sea.

In Mexico's Guadalupe Valley, you can sample south- of-the-border vintages at Chateau Camou. Mexico's Guadalupe Valley is dotted with vineyards like Chateau Camou.Adobe Guadalupe is one of the few lodging choices in Mexico's wine region.