Osha Thai's sisterhood of success

When sisters Wassana Korkhieola and Lalita Souksamlane needed a name for their Thai restaurant in the Tenderloin, they went with the royal Thai word for "delicious."

But there was another, much more pedestrian, reason that made the name Osha Thai so appealing.

"It's easy to say," Souksamlane admits with a laugh.

With food as palatable as its name, Osha Thai has grown into one of the best-known ethnic restaurants in San Francisco. What began as a tiny, no-frills spot on Geary Street has become a full-fledged empire known for swanky presentation and decor.

Osha Thai opens its seventh location this week, taking over the former Bong Su space near Yerba Buena Center for the Arts.

To meet Souksamlane, 39, and Korkhieola, 37, is to see Osha's style come to life. The sisters are immaculately dressed from head to toe, and they're as prone to chat about fashion as they are the latest stemware and serving plates.

Both were in their 20s when they came to the United States from Nongkhai in northeast Thailand to study and work. Souksamlane had gone to culinary school back home, and Korkhieola's then-boyfriend was such a fan of her cooking that he suggested they open a restaurant of their own.

He came across a "For Sale" advertisement in the newspaper for the space on Geary, and the next day chipped in $30,0o0 to take over the restaurant.

So began Osha Thai, in 1996. The sisters worked in the kitchen, serving simple street food such as pad Thai, pad see ew and fried rice, while the boyfriend washed dishes. They struggled at first, selling about $700 worth of food a day, but eventually built up enough of a customer base to expand next door.

Today, most entrees are $10 to $20, and while the traditional pad Thai and curries remain on the menu, it's the newer fusion items that stand out. The Osha tartare appetizer includes tuna, cilantro, mango and avocado in a sriracha-sesame sauce. Volcanic Beef, the restaurant's signature dish, features grilled flank steak topped by a tower of onion rings and herbs and overflowing with "lava sauce" that can also be purchased by the bottle.

Souksamlane says she's incorporated more vegetarian options to reflect the Bay Area clientele and constantly experiments with new flavor combinations at home.

"The concept at Osha isn't high end," she says. "We want people to be able to eat here all the time. We want them to enjoy the food, enjoy the atmosphere, enjoy the service."

Osha's hours are among the most generous in town: All locations are open until at least 11 p.m., with the noodle shop on Geary open until 3 a.m. on weekends.

It was through long hours there, after all, that both sisters met their husbands.

Nuttawat Wongpisethkul was a regular at the Geary location - "It was the best in that area," jokes Wongpisethkul - before mustering enough courage to introduce himself to Souksamlane.

Wongpisethkul, who studied interior design in Thailand, helped the sisters expand Osha next door in 1999. Within about a year, he and Souksamlane were married, with children.

Korkhieola, meanwhile, eventually parted from her boyfriend. She met her husband, Derek Shotiveyaratana, at a restaurant supply shop. His father owns Aroi, another Thai restaurant in the Tenderloin.

With Osha Thai's growing success, the sisters split the management of the restaurants - Souksamlane runs the three locations downtown, while Korkhieola looks after the neighborhood outposts in the Tenderloin, Mission, Cow Hollow and Glen Park.

The sleek look all Osha Thais boast is the work of Wongpisethkul and Korkhieola, who have designed the interiors for their respective restaurants. The in-house culture extends to Osha Thai's employees, most of whom are Thai. The sisters and their husbands, who help manage the restaurants, take the entire staff to Lake Tahoe every year, and employees show off their vocal cords during karaoke contests.

Korkhieola says her older sister is more mature, more organized. Souksamlane says her younger sister is more outgoing and detail oriented. Together, they've made Osha a formidable force.

"She's more Thai contemporary, and I'm more modern and trendy," Korkhieola says. "It's a good fit."

Osha Thai Restaurant, 311 Third St, S.F.; (415) 896-6742. Also 819 Valencia, S.F.; (415) 826-7738. 149 Second St.; (415) 278-9991. 4 Embarcadero Center; (415) 788-6742. 2033 Union St.; (415) 567-6742. Osha Thai Cafe, 696 Geary St.; (415) 673-2368. Also 2922 Diamond St.; (415) 586-6742.

E-mail Janny Hu at jhu@sfchronicle.com.

This article appeared on page E - 1 of the San Francisco Chronicle