San Franciscans are well accustomed to waiting outside Tartine Bakery for their croissant or loaf of country bread. But the lines outside the bakery’s first Seoul outpost, which opened Jan. 27, make the hometown shop look like a convenience store.

Chad Robertson, who owns Tartine with wife Elisabeth Prueitt, said that for day one his team prepared as much food as they would for their Guerrero Street shop — and sold out in just a few hours.

Tartine is not the first local bakery to open in the South Korean capital. That would be Mr. Holmes Bakehouse, Aaron Caddell’s Instagram-magnet Tenderloin store, which opened a branch in the stylish Apgujeong neighborhood in December 2015. Belinda Leong and Michel Suas’ B. Patisserie is following Tartine to Seoul, with a projected premiere of late April.

Well-traveled Korean entrepreneurs, not to mention a thriving pastry scene in Seoul, are enticing some of San Francisco’s best pastry chefs to expand to Asia. South Korea, as the Winter Olympics demonstrated once again, has become an economic and cultural powerhouse, and Seoul is a megacity with 25 million inhabitants. Several Korean bakery-cafe chains have thousands of locations across the country. In the past few years, Paris Baguette, perhaps the best known, has expanded to the Bay Area and Southern California.

“It’s not at all unusual now to see people who’ve trained at the CIA (Culinary Institute of America) or Le Cordon Bleu coming home (to Korea) to set up their own shops,” Jennifer Flinn, an assistant professor at Kyung Hee University in Seoul and a food writer there for more than a decade, wrote in an email. “And many of them are doing wonderful, innovative things with local flavors and ingredients.”

Yet San Francisco’s reputation has a wide reach. Several of Tartine’s baking books have been translated into Korean. Doug Cho of Seoul’s CNH Holdings, the man responsible for bringing B. Patisserie to Seoul, explained in an email, “San Francisco has been known for being cradle of numerous startups. Seoul might be very open to accept new trends.”

According to B. Patisserie’s Leong, Cho approached her and Suas last year proposing to open a location in Seoul that combined their two Pacific Heights businesses, B. Patisserie and B on the Go.

The pair have since made several trips to Korea to set up the kitchen, and Korean bakers have traveled the opposite way to train in San Francisco. In the meantime, Leong and Suas are tweaking their recipes to accommodate Korean flour and the style of French butter sold in Asia.

The Seoul location, Leong said, is also a way to give B. Patisserie’s loyal bakers, some of whom have worked for her since the shop first opened, new opportunities.

“Korea’s really up and coming. They really appreciate, and are excited about, Western food,” Leong said. “We’re opening at a good time. I think it’s great that Tartine is opening there, Mr. Holmes is there. Makes it a little less scary.”

San Francisco restaurants have been more likely to open restaurants in Asia than Europe — more likely, even, than elsewhere in North America — since 1998, when Jeremiah Tower sold his San Francisco blockbuster Stars and helped its new owners open Stars Singapore and Stars Manila.

For the past decade, however, Tokyo has been the primary overseas destination for Bay Area food companies: A16, Blue Bottle, Verve Coffee, Wise Sons Jewish Delicatessen and, yes, Tartine Bakery, which is also working on a Tokyo shop.

Shelley Lindgren, owner of A16, said that partnering with a Japanese restaurant group nine years ago to open a Tokyo restaurant of the same name has been great for her company, though not a huge profit-generator. She and other members of her team travel to Japan several times a year and host Japanese cooks in their kitchen. “The cultural exchange has been something that is invaluable for our whole team,” Lindgren said.

Licensing deals like the ones A16, Mr. Holmes and B. Patisserie have signed are almost easy bets, because the Asian partners take on all the financial risk.

“As far as construction and rent and employee costs, that’s with him,” Leong said. “It’s a way for us to expand with no financial cost, but at the same time, it’s our reputation. We have to make sure to keep up the quality.”

Expanding in Asia instead of the United States may, paradoxically, help small San Francisco restaurateurs keep their artisan credentials at home. Even though all the American restaurateurs The Chronicle spoke to praised the talent and devotion to detail of their Korean and Japanese partners, missteps in Asia won’t damage the core brand the way one in New York or Las Vegas might.

Robertson and Prueitt could have signed that kind of deal. But they’ve taken on an even more ambitious task. Not only are the Tartine owners running the Seoul branch with one of their partners in the U.S. business, they’re opening a coffee-roasting facility and recruiting Korean farmers.

“Since I’ve embraced growing Tartine, I’ve been able to develop relationships with farmers and get them to grow the grain varieties I want and mill it,” Robertson said. He sees this work as part of his larger mission to build a market for sustainably grown, heirloom grains. “I can’t affect that too much if I’m staying small.”

In the meantime, Robertson is shipping tons of American wheat, milled at the San Francisco branch of Tartine Manufactory, to Seoul. The bakery has set up an exchange that has sent more than a dozen staff members to Asia so far and brought the head bakers from Seoul to San Francisco.

In Seoul, Tartine first-viewers waited so long on one below-freezing day the line drew national press, which got even more residents curious to try this reportedly amazing San Francisco bread. The demand has been so high that a second Seoul location is in the works.

Things happen quickly in Korea: It’s already slated to open in July.