Light a grill fire. Grill the eggplant over the open fire or gas flame, turning them frequently, until the skins are black and parched and the flesh feels soft when pierced with a fork, about 18 minutes. (Alternatively, prick the eggplant in several places and roast on a foil-lined baking sheet in a 350°F oven until soft, turning two or three times, about 1 hour.) When the eggplant are cool enough to handle, peel the charred skin and put them in a colander to drain. Squeeze the eggplant gently to get rid of the extra moisture and chop the pulp. Set aside. In a small bowl, combine the coriander, cumin, turmeric, cayenne, and a little salt; set aside.
Heat the oil in a skillet and fry the onion over medium-high heat until golden brown, about 30 minutes. Add the garlic, ginger, and fresh chile and cook, stirring frequently, until fragrant. Add the spice mixture and cook, stirring a few seconds until fragrant. Add the tomatoes and cook over medium heat until the tomatoes are soft, about 5 minutes. Stir in the eggplant pulp and the chopped cilantro. Cook, stirring often, until all the liquid in the pan evaporates and the oil begins to separate and forms a glaze over the mixture, about 20 minutes. Taste and add salt if needed. Serve in a bowl sprinkled with more cilantro leaves.