A specialty in many a Bengali-speaking home kitchen, this curry is flavored with one of Bengal’s key spices: poppy seeds (poshto). When roasted and ground, poppy seeds are very nutty and sweet, with an ever-so-slight bitterness. I like to serve this with some Lime-Flavored Rice with Roasted Yellow Split Peas and Nutty Cheese in a Spinach-Chickpea Flour Sauce.