The yen-ta-fo soup at Sisters: The Living Room Cafe in Fairfax, Va. (Eva Russo/For The Washington Post)

The second you step inside Sisters: The Living Room Cafe in Fairfax, you’re served a heaping platter of cognitive dissonance. Whatever expectations — some might call them stereotypes — you have about Thai restaurant decor will be shattered in one startling glance around the room. The place feels like home.

The shelves along one wall are crammed full of books, knickknacks and action figurines bent into battle poses, leaving the impression that a small pack of boys just wandered off to play Xbox in another room. The tables and chairs, all mismatched in size and style, look as if they were pulled from every corner of the house for a large dinner party. Framed portraits cover another wall, every face a stranger, a reminder that this isn’t a friend’s home after all, but a commercial restaurant.

Opened in January, Sisters is the debut eatery from Sumontita Disayawathana and her husband, Jaturon Srirote. They named the place for their young daughter and a niece — not sisters obviously, but, as Disayawathana says, “they love each other like sisters.” Sisters’ warm, family setting plays a dual role: It pays homage to Thailand’s home-style eateries and the family restaurateurs who live above the shop, and it helps Disayawathana pass the long hours required of a restaurant owner.

“I want to feel at home, so I can be happy all day long,” she says.

The cozy cottage atmosphere is not the only thing that makes me happy at Sisters. There’s a “decoration” on a wall in a discreet corner: a menu separate from the scrapbook-style one handed to you upon arrival. The wall menu is written in Thai and, as a server explains, is entirely devoted to Thai street food. The sound you just heard was my heart skipping a beat.

To me, this kind of secret menu is the missing railroad switch in many Thai restaurants. Most places merrily roll along well-worn tracks, serving standard-issue dishes, but a few spots, such as Nava Thai and Vannipa Thai, flip the switch and barrel down a more exciting line, where there’s all kinds of surprises.

The tricky part of parsing chef Prasert Limsumang’s street-food menu, at least for those who don’t speak Thai, is relying on the wait staff to provide translations, which can be an ad­ven­ture in the young leading the ignorant. Hilarity can ensue as one of the gracious 20-something servers tries to explain, for instance, the finer nuances of gang pa, otherwise known as jungle curry. Our waitress told us it was a nuclear-hot dish called “In the Jungle,” which only made me think of Jethro Tull.

As it turns out, gang pa is a curry dish without coconut milk, designed to cut down on the calories while ramping up the heat. My version at Sisters was a brothy affair — the kitchen served it with beef and chicken, though typically you pick a single protein — and it smacked more of Thai aromatic spices than of chili pepper heat. The pad ped pla grob, or spicy crispy fish (also from the street food menu), generated more fireworks with its golden squares of fried tilapia, which remained crisp despite a light application of wickedly hot sauce. I really didn’t want to share.

Neither of these dishes, though, was as complex as the yen ta fo. This soup (again found on the special menu) may look innocuous with its pinkish broth swimming with seafood, but its beauty conceals a small, surprising bite. The wide, flat noodles at the bottom of the bowl — rice ribbons as absorbant as sponges — ferry every salty, sweet, sour and spicy note, with the bonus of providing a bit of texture. The soup satisfies as much as any entree, especially if you doctor the broth with one of Sisters’ four tabletop condiments, which range from hot to face-melting.

Plenty of spicy temptations lie within the regular scrapbook menu, too (not to mention sweet handwritten notes from diners, such as this: “We’re here with our daughter! So hungry!! So glad!!”) First among equals is Limsumang’s crispy duck kapow — slices of roasted bird battered, fried and smothered in a chili-garlic sauce that neither affects the crunch nor the lush gaminess of the meat. I found the fried rice in his kaw obb on the greasy side, which did nothing to stop me from wolfing down the shrimp, scallops and carved squid buried under the scorching grains tucked into this hot pot.

The appetizer list is a minefield. The fried chicken wings stuffed with crabmeat (dubbed “angel wings”) are bland and sinewy, while the steamed dumplings boast a jewelry-like precision, their meaty interiors enrobed in wrappers as thin and refined as filigrees.

The app that impressed me most, however, was the chicken green curry, which comes with triangles of roti, the buttery, Indian flatbread that rarely manages to weasel its way onto American-style Thai menus. Spoon some curry onto the roti, then seal it like an improvised spring roll, and you’ll find that the flatbread performs various acts of kindness to the spicy mixture, not just softening its heat into something delicate, but also adding a layer of richness otherwise absent from the dish.

It’s clear that Sisters’ ability to expand the Thai restaurant experience is not limited to the decor.

Sisters: The Living Room Cafe

4004 University Dr., Fairfax. 703-267-9619.

Hours: Monday-Thursday 11 a.m. to
10 p.m.; Friday 11 a.m. to 10:30 p.m.; Saturday noon to 10:30 p.m.; Sunday noon to 9:30 p.m.

Nearest Metro Station: Vienna, with an additional 3.7-mile trip to the restaurant.

Prices: Entrees, $10.75-$15.50.