It can be tricky to find authentic Thai food in the US. How can you tell if your favorite local Thai restaurant is serving food you might find in Bangkok? We asked food writer Leela Punyaratabandhu—the brains behind the Thai cooking blog SheSimmers and author of the cookbook Simple Thai Food—for some direction on what makes Thai food authentic. But don't despair if your favorite local spot doesn't check all the boxes. There's definitely more than one way to enjoy your meal.

1. A Menu of Thai Food and Thai Food Only

A Thai restaurant that boasts Thai and another distinct cuisine might not be putting its best efforts into either one.

"If they happen to have really good, authentic Thai food—which is not impossible, but it's very unlikely—it makes me question why they can't just pick one [cuisine]," Leela said. "You wouldn't want to walk into a sushi restaurant that serves Thai food, so why would want a Thai restaurant that serves sushi?"

2. The Smaller the Menu, the Better

Look for a restaurant with smaller menu or one that sticks to a single region in Thailand. For an example, consider Nong's Khao Man Gai in Portland, Oregon. The hugely popular food cart only serves a single dish: its namesake khao man gai chicken and rice. That's a far cry from menus that list dishes from all over Thailand.

"If you see green curry and red curry and pad thai and a lot of other things that don't normally coexist, that's rare," Leela said. "It happens in restaurants that cater to tourists."

3. Nix the Chopsticks

"[If] you go to a Thai restaurant and they preemptively bring out a pair of chopsticks, that's not a good sign," Leela said. "It means they're used to catering to people who don't demand authenticity."

In Thailand, rice isn't eaten with chopsticks; diners use forks and spoons. "The fork pushes the food into the spoon, transporting both the sauce and the rice. But if you transport that same bite with a fork, all the liquid falls through," she said. "It's even worse when you use chopsticks."

4. Ask to See the Secret Menu

What are the restaurant's staff members eating? Secret-menu items.

"The real secret menu, you're not even supposed to know about it," Leela said. "These are the things that [staff members] know no one else but Thai regulars would order—the things they would make for themselves."

But the good stuff isn't always hidden away. The newer generations of Thai chefs, such as Kris Yenbamroong of Los Angeles's Night + Market, are bolder than those of the past. "They know that we have reached a point where Americans are ready for authentic Thai, and they don't hold back anymore," Leela said. "We have now entered the era where the things they would make in the back of the kitchen are now on the regular menu."

5. No Crab Rangoon

Leela hadn't heard of crab rangoon until she came to the United States: "I have never seen crab rangoon in Thailand. Ever."

The same goes for Vietnamese-style rice-paper spring rolls, which are the US standard. "Back in Thailand, it's a whole different thing," she said. Authentic Thai spring rolls are made with thin, wheat-based wrappers. So if the Thai restaurant you're at opts for these wrappers, it's the real deal.

6. Pass the Nam Pla Prik

Although not all authentic Thai restaurants serve nam pla prik—a condiment of fish sauce and chilies—its availability is always a good thing, Leela said. "That's a sign they they care for you in the way they cook and do hospitality." As Leela mentioned on her blog, asking for nam pla prik is a quick way to endear yourself to the restaurant staff.