These soft-on-the-inside and crispy-and-charred-on-the-outside flatbreads have a secret ingredient: cooked potato. It keeps them pillowy and flexible and ideal for stuffing with feta cheese and slathering in zaatar oil. But if you take away nothing else, let it be the delicious eggplant dip that accompanies these flatbreads, which is easy and simple and can be your go-to late summer side dish.