In the SoMa neighborhood of San Francisco, the winds pick up off the waterfront, chilling a line of people waiting patiently to get their hot bowls of barbecue rib eye, chicken or spicy pork with kimchi fried rice. The breeze carries the smell of tantalizing grilled meat, teasing those shivering and salivating nearby.

Seoul on Wheels is not your typical lunch truck. Although it offers the usual array of fruit, chips and sodas and has that familiar spigot on the side of the truck that pours hot coffee, this restaurant on wheels specializes in Korean fare.

In a city famous for its international cuisine, Korean food is hard to come by. A few restaurants run along a strip in Japantown, which is nothing like the sprawling acreage of L.A.’s Koreatown that Julia Yoon, an Orange County native, grew up with.

The 37-year-old got the idea for her lunch truck some years ago when she first arrived in San Francisco. Lunch trucks featuring ethnic cuisine were commonplace. It didn’t take a genius to figure out that the formula of food on wheels could be applied to Korean barbecue. And Julia saw a way to fill a hole in the industry while also satisfying her own cravings. At first, however, she was wary of breaking into the food business.

“I don’t know sh-t about running a restaurant,” she explains, “but I like to eat.”

Six months ago she finally took her idea on the road.

Julia may not have invented the wheel, but she may have been the first to install a grill — instead of the usual griddle — inside a food truck. After all, she wanted to serve authentically grilled barbecue, and a giant frying pan simply wouldn’t do.

Already covered in the food section of the San Francisco Chronicle and posted all over Yelp! and other food blogs, Julia’s brainchild is keeping her busy and popular. In fact, her biggest stop was recently added to her route because the huge offices of AKQA, an interactive advertising company, invited her to park at 2nd and Townsend and feed its workers, many of whom are bored with the typical lunch fare.

On this Tuesday afternoon, Julia has only been parked at AKQA a few minutes, but already the line snakes toward the end of the block. Some are first-timers, having been encouraged by co-workers. Some don’t know anything about Korean food. One guy even asks his buddies, “What’s kimchi?” After a pause, his friend replies: “I think it’s cabbage.”

It’s surprising that a city with a huge pan-Asian population and a varied culinary culture might find Korean food exotic and Seoul on Wheels a novelty. But Julia hopes by making the cuisine mobile, she’ll help make Korean food “as ubiquitous as Chinese or Japanese food.”

To do this, Julia — who calls herself the “BBQ Princess of Yoon, from the Province of Yummii” on her Web site — wakes up at 3:45 a.m., preps in a commercial kitchen, and reaches her first stop by 6:30 a.m. Seoul on Wheels makes seven stops in SoMa, and though she and her non-Korean chef, Julietta, can’t grill while in motion, they do cook all day whenever they can. Still, they always run out of food, and it’s not uncommon for Julia to call out to her long line of customers: “Sorry, we’re out of chicken, guys. But we still have spicy pork!”