FROM THE SIDEWALK on SE 28th, all you can see of Lang Baan are the tops of succulents in rough wood planters; a shade obscures the activity within. On the outside, there are no indicators and no warning of this wondrous new restaurant, beyond the growing word of mouth that this is the place to eat right now if eating is your thing.

Admission comes via a reservation for one of two nightly seatings held Thursdays through Saturdays, and through the front door of PaaDee, itself among the most solid street-style Thai restaurants in town. A top-knotted waitress ushers your party to the back, pulls a handle on a false bookshelf and leads you into the open kitchen and tiny dining room, where PaaDee's Akkapong "Earl" Ninsom is already laying out the betel leaf for the first course. This is where you and a select few will spend the next two hours of your life sampling 10 to 13 courses of Thai tastes and textures rarely seen outside of Siam. Ain't nobody got time for chicken pad thai up in here.

Diners choose between a slightly pared-down no-substitutions prix fixe option (originally, it was $40; this month it's $45) or go full "let's get the lobster" tilt for $60. You'll leave sated—physically and culinarily—with either selection. The menu shifts monthly: In May, ancient and Northern Thai recipes starred, while June moved to Central Thailand and hung on to several plates from the month before. It makes the whole experience largely addictive, compelling you to return and taste each new plate before it disappears.

There's the first course, a pineapple and pork belly crumble hit with roasted coconut sauce and fish sauce-sautéed shallots, tucked neatly into a betel leaf wrap. The sweet, savory, and salty elements zap each taste bud on its way down your throat—a shot across your palate's bow. You're instantly mad there isn't more of it, but you'll be glad there's room for what's to come. Sticky rice is infused with watermelon, roasted, and crisped into a cake, topped with a meaty relish of roasted coconut, pork, and peanuts. June's yum talay celebrated an Oregon catch of squid, razor clams, and spot prawns so delicately poached they kept their raw texture, swimming with pickled ginger and citrus wedges in a chili-lime dressing.

Ninsom and his right-hand chef, Rassamee Ruaysuntia—an alumna of Bangkok's fine-dining scene—spend the week preparing their tinctures of fish sauce, hot chilies, tamarind, and coconut, leaving à la minute cooking for service.­­ Order a crisp cocktail from the PaaDee bar, like the Koh Samui, with gin, egg whites, and lemon ($11) or a light beer (the $30 wine pairing isn't necessary). Take a sip just before tucking into the fiery hot chili relish of crispy catfish, pork belly crumble, and salted duck egg—a riff on a favorite dish from Bangkok's famous Or Tor Kor Market—served with cool herbs, greens, cucumber, and mango on the side. The spice cut through my summer cold and had me crying uncle (in a good way), until a dish of fermented pork sausages and fried acadia leaves in fermented rice broth appeared at just the right moment to turn the dial back to mild.

There was also a stunning curry of grilled wagyu coulotte, the only use of beef on the menu: pink slices cooked to rare perfection, soaking in a light curry that packed a wallop of heat that made the coconut rice below a welcome addition.

Desserts—heavy on the coconut and frozen elements, including a duck egg and coconut ice cream with salted corn, peanuts, and caramelized sweet potato—touched the meal down with the finesse of a veteran pilot making a water landing in the Gulf of Thailand.

Each menu featured small missteps: In May, a portion of king oyster mushroom and trout chili relish was far too meager and mild to stand up to the fresh greens it was served with, and June's mee grob—a crispy angel hair noodle nest with shrimp, pork, and a fried omelet with orange zest in a caramelized fish sauce—came out one-note and slightly greasy. This, however, is parsing lemongrass strands. Service was cheerful and relaxed. Our waitress happily took back a recommended cocktail that turned out to be too sweet to stack with the heat of the meal.

While PaaDee is billed as Thai comfort food, its hidden jewel, Lang Baan, is pushing far outside of those cozy confines and into the exciting realms of refined and challenging plates. Like a salmon ceviche with Thai eggplant and orange, Lang Baan is the kind of thing Portland didn't know it needed until it was served to us, perfectly spiced.

Thursday–Saturday, two seatings at 6 and 8:30 pm. Reservations pretty much mandatory, but drop-ins welcome if there are seats.