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.