This stew is a much-simplified version of Indian chole baigan, an eggplant and chickpea curry. Instead of using a slew of spices, we reach for only curry powder, but we build depth of flavor by cooking the tomato paste and curry in oil until the mixture begins to brown. And to speed along the cooking, we make the sauce on the stovetop while browning the eggplant and onion under the broiler. Canned chickpeas also make the stew a breeze to prepare. The best tool for shaving wide zest strips from the lemon is a Y-style peeler, but try to remove only the colored skin without taking much of the bitter white pith just underneath. Serve the curry with warmed naan and basmati rice.