Iara, a new Amazonian-Brazilian restaurant, is named for a river spirit from the folklore of the Tupi and Guarani peoples; half woman and half fish, she’s something like a vengeful mermaid, a freshwater siren who lures men down into the deep with her singing. The first thing you see at her namesake establishment is a glass-fronted case of silvery tilefish, hung up to dry-age. Then the room gives way to a riot of wildly colorful walls, twirling and twining greenery, wood carvings and wall fixtures, wooden tables slashed with a stripe of rain-forest green, the clatter and whoosh of cooks in an open kitchen, and the heady aromas of smoke and spice. The restaurant’s chef-owner, Vitor Mendes, was most recently chef de cuisine at Theodora, in Fort Greene, which is known for its dry-aged seafood and excellent use of an open-flame grill. He’s brought both of those things with him—though the grill at Iara burns charcoal, rather than Theodora’s wood.

There are plenty of Amazonian ingredients to be found on the menu: cupuaçu, a relative of cacao; coumarou, also known as tonka bean, an analogue to vanilla; puxuri, a nutmeg-like spice that, at Iara, rims the glass of a lusty coconut-milk cocktail. But the most vivid through line in Mendes’s cooking is cassava, the world’s great polymathic tuber. It appears as a featherlight, tostada-ish rectangle under a layer of charred-pineapple relish and pearlescent slices of raw scallop. It comes in the form of tapioca—cassava’s starch, extracted—in a traditional pão de queijo, chewy little spheres that arrive with a trio of dips: pink guava; white requeijão, a mild and creamy cheese; and dark, smoky eggplant. Fermented cassava juice becomes tucupi, a tangy golden-brown liquid that’s used in the juicy hot-sauce set on every table; it also kisses a Martini punched up with soju and preserved-lemon brine; and deepens the vinaigrette on a hiramasa ceviche. It’s also the base for the broth in Iara’s tacacá, a soup from northern Brazil, where it is a popular street food in Amazonian cities such as Manaus and Belém. Mendes’s version is a composed take, with silky white beans and caramel-sweet morsels of roasted plantain, its surface dotted with green ribbons of oil infused with jambu, a mild herb that produces a sparky, tingly numbness on the lips and tongue, like an electrified Sichuan peppercorn.

New York is not short on Brazilian food, but it tends to arrive in predictable formats. At churrascarias, waiters circulate with hunks of meat on swords. At quick-service counters in the outer boroughs, tias sell coxinhas and pão de queijo by the dozen. And at home-style comida-caseira places the menus tend toward variations on rice, beans, and meat. A meal at Iara, with its specific and near-hagiographic focus on the indigenous ingredients of the Amazon, is almost nothing like any of these. If you haven’t had the good luck to dine widely in Brazil, much of the menu will feel thrillingly novel. Here in the U.S., I’ve previously encountered jambu as a novelty foodstuff, in its flower-bud form, under the frankly demeaning name “buzz buttons.” Mendes, who was born in Brazil, is an exuberant teacher. He immigrated to the U.S. as a child, and he was awakened to the vast fecundity of the Amazon Basin when he returned to Brazil as an adult, after his father’s death. His passion for these ingredients is palpable, and seems to have infected his staff. A server might linger for a moment to watch you take your first sip of a Romeo and Juliet Martini, a play on Brazil’s ubiquitous guava-and-cheese snack involving mezcal ingeniously washed with mild minas cheese. (The cocktail list was created by Calvin Czypinski, another Theodora alum, clearly having fun.) Another, dropping off a dish of picanha steak, might urge you to pay close attention to the creamy sauce au poivre upon which the meat is set, noting that it’s made not with run-of-the-mill peppercorns but with jiquitaia, a blend of dried hot peppers from the Baniwa people.

My favorite spot in Iara’s well-proportioned dining room is at a chef’s counter that rings the open kitchen. Sitting at a dining bar can sometimes feel tedious and penitent; here, it’s more like being pressed up against the stage at a rock show: the noise, the energy, the pyrotechnics! What a rush it is, watching a cook turn roseate pieces of tilefish over a roaring grill for a portion of the Bahian coconut-broth stew moqueca. Sure, Bahia isn’t an Amazonian state, but the dish fits right in: it comes slicked with red palm oil, in a clay pot sized for sharing, with individual sidecar bowls bearing toothsome white rice, farofa (seasoned, toasted cassava flour), and bright slashes of pepper relish. The battalion behind the counter whips and chops and sauces, looking up at the audience of diners only rarely while flying from one station to another with a forceful grace.

The restaurant is at its strongest when it’s most Brazilian, and weakest when it’s making concessions to what’s hot here in New York. A starter of raw tuna draped over fried puffs of tapioca is a clever enough riff on a ubiquitous crispy-rice sushi appetizer, but does the world really need more of that? A “palmito carpaccio” salad bore a few paper-thin rounds of fresh hearts of palm arrayed atop a nice but largely unexceptional chiffonade of chicories and other winter greens. It certainly can’t compete with an off-menu special of tambaqi, an Amazonian river fish, grilled until sizzling, butchered into hunks of collar and rib and fillet, served with a pile of tapioca fries and an açaí ketchup, piquant and sour and Tyrian purple. End your meal with pudim, a condensed-milk flan speckled with sesame seeds, or a couple of brigadeiros, Brazil’s famous chocolate bonbons. Or, if you still haven’t had your fill of cassava, try the bolo de mandioca, a sweet, coconutty cake whose density and tenderness come from the root, finely shredded into the batter. It’s crowned with a sphere of coconut-lime sorbet—a halo, a sun, a disco ball—a bit of sharpness to slice through the magnificent density of the Amazonian rain forest. ♦