HOUSTON — The Hughie’s on West 18th Street is one among scores of Vietnamese American restaurants around this city. But it may have more in common with a Dairy Queen.

For starters, it used to be a Dairy Queen. The sign out front still has the eye-shaped outline of the ice-cream chain’s logo. On the menu, alongside banh mi and shaking beef, are thickly crusted, buttermilk brined chicken tenders, a Dairy Queen standard.

The most striking similarity, though, is the restaurant’s drive-through window, which opened in March 2020 in response to the coronavirus lockdowns.

Paul Pham, an owner of this Hughie’s and another a few miles away, hopes that one day, his restaurant will be as ubiquitous as Dairy Queen. Next year, he’ll open a third location, and has plans to expand in Texas and perhaps beyond.

In his vision, the drive-through — a classic American innovation that harnessed the fast-food business to the nation’s car culture — is also a potential vehicle to make Vietnamese food the next cuisine to join that success story. He believes that Americans’ increasing familiarity with Vietnamese cuisine makes it the ideal food for the next generation of drive-through restaurants.

In recent years, several Vietnamese restaurants with the same idea have opened in Houston, including Oui Banh Mi, Saigon Hustle and Kim’s Pho & Grill. Outside Texas, there’s Simply Vietnam in Santa Rosa, Calif.; Mi-Sant Banh Mi Co. in Brooklyn Park, Minn.; and To Me Vietnamese Sub in Calgary, Alberta.

All these restaurants have drive-throughs, and owners who are trying to attract a broader fan base for Vietnamese cooking by marrying its flavors with American convenience.

“We are going to shift toward more of a Chick-fil-A type of concept,” said Mr. Pham, who was born and raised in Houston, home to about 150,000 Vietnamese Americans, one of the largest Vietnamese populations in the United States. “They are the godfather of this business, right?”

To him, that also means using technology to streamline customer service, opening in diversely populated neighborhoods and closing on Sundays, as Chick-fil-A does — practices, he said, that are less common among Houston’s older Vietnamese restaurants.

“Our concept would not survive in an old-school Asian environment,” he said. His family opened the first Hughie’s in 2013.

Americans who identify their background as Vietnamese numbered roughly 2.1 million in the 2020 census. Many North American cities, including Philadelphia, Washington and San Jose, Calif., are experiencing a surge of new Vietnamese restaurants.

But in adopting the drive-through and other practices of the fast-food industry, restaurateurs hope to reach an audience beyond their fellow Vietnamese Americans.

“We are trying to sit at the level of Panda Express,” said Cassie Ghaffar, an owner of Saigon Hustle, which she opened last February in the Oak Forest neighborhood of Houston, with her business partner, Sandy Nguyen.

Saigon Hustle — which serves banh mi, bun (vermicelli bowls) and com (rice bowls) — looks like an American drive-in from the 1950s, with a large awning decorated with images of dragon fruits, and an area where cars can pull up. Saigon Hustle only has one location, but its founders said it is on track to take in $1.8 million in revenue this year. They plan to expand nationally in two to three years.

For many diners who aren’t Vietnamese, a trip to Chinatown for Vietnamese food can be a challenge, as the menu may not be in English, while the more upscale Vietnamese fusion restaurants can feel prohibitively expensive, said Ms. Ghaffar, 40.

“The drive-through is less intimidating,” she said. “It is giving more people an opportunity to try Vietnamese cuisine.”

The drive-through, which emerged in the mid-20th century and flourished in the 1970s, has primarily been a conduit for foods like hamburgers and French fries. Fast-food chains selling Mexican American food, like Taco Bell and Taco Cabana, have also widely adopted it.

The drive-through found new life during the early days of the pandemic, when many restaurants embraced ways of limiting person-to-person contact.

Kenny To and Hien Nguyen opened To Me Vietnamese Sub in October 2020 in Calgary. But their drive-through was inspired less by the pandemic than by the Canadian fast-food chain Tim Hortons.

“Every morning I have to have a coffee at the Tim Hortons drive-through. It is very convenient for me, for my everyday life,” said Mr. To, 60. “I was thinking, why not have the Vietnamese submarine drive-through?”

Vietnamese dishes like banh mi and spring rolls are portable and easy to package, Mr. To said, making them well-suited for a drive-through format. But because he takes special pains with his banh mi, making each part to order and even baking the bread, it’s harder to make them as quickly as other fast-food items like burgers and fries.

“You have to bake the sub, and then with the meat you have to cook it nicely,” he said. Sometimes, customers have to wait as long as 30 minutes.

Mr. Pham, of Hughie’s, said a major barrier to national expansion for a restaurant like his is the limited availability of certain ingredients. A condiment like Golden Mountain Seasoning Sauce, which he uses in marinades, may be hard to find in areas without large Asian American populations.

But at least one Vietnamese fast-food restaurant has already figured out how to scale up nationally: Lee’s Sandwiches, started in San Jose in 1983 by Ba Le and Hanh Nguyen. Today the chain has 62 locations in eight states, including California, Nevada, Oklahoma and Texas. Several have drive-throughs.

The restaurant’s expansion, which began in 2001, came with limitations. “Back then, we were a little more cautious,” said Jimmy Le, the vice president of Lee’s and the grandson of the founders. The company chose only areas with significant Vietnamese American populations.

Even though Lee’s has since opened restaurants in areas with more multicultural populations, half of its locations are still in predominantly Asian American neighborhoods, said Mr. Le, 40.

He said he was happy to see all the new Vietnamese drive-throughs. But he isn’t trying to turn Lee’s into an American fast-food chain. “We don’t want to change too much, or change at all,” he said. “People know Lee’s Sandwiches, and they know what they are going to get.”

It’s hard for Mai Nguyen, 58, another longtime Vietnamese American restaurateur, to feel excited about these newer restaurants. She has run the beloved Vietnamese restaurant Mai’s, in Houston, since 1990; her parents opened the place in 1978.

“What I see is the generation now, they kind of make the restaurant look very nice and modern,” she said. “But I don’t see the food is authentic.”

Yet authenticity has a different meaning for these restaurateurs, most of whom grew up outside Vietnam.

At Mi-Sant, in a Minneapolis suburb, it means serving not only traditional banh mi but also croissants — a specialty of an owner, Quoc Le, 37, whose father received his pastry training in France — out of a drive-through in a former KFC.

“This is part of our identity,” said Linh Nguyen, another owner, along with her three sisters and brother. “Growing up, seeing a drive-through, it wasn’t anything out of the ordinary for us.”

She wants Mi-Sant, which opened in 2018 and has another location in the area, to emulate upscale fast-casual restaurants like Shake Shack. But she acknowledged that her reaching out to a wider audience may have alienated her Vietnamese customers.

“I didn’t have all Vietnamese-speaking employees who could talk to them,” she said. “There were no Vietnamese words on the menu, so they couldn’t read it, and our price point is a lot higher” than that of many longstanding Vietnamese restaurants in the area.

And some diners still aren’t accustomed to ordering a banh mi through a drive-through. “We get people that will just come and order a burger and taco, and it is really funny,” said Ms. Nguyen, 33. “I have to be like, ‘We don’t do that here.’”

For Mr. Pham, modeling Hughie’s after American fast-food restaurants isn’t just a way to attract more kinds of customers, but a reflection of his upbringing in Houston.

“The menu, and having those two different types of worlds combined, is pretty much me,” he said.

To do it any other way, he added, would feel inauthentic.