Position rack in upper third of oven; preheat to 400 degrees F. Line a large rimmed baking sheet with foil.
Cut each eggplant in half lengthwise. Using a spoon, scoop out flesh from the halves, leaving about ½-inch border on the sides and bottoms. Coarsely chop the flesh and set aside.
Drizzle the insides of the eggplant shells evenly with 1 tablespoon oil. Place the shells, cut-side up, on the prepared baking sheet and roast until tender, 20 to 25 minutes. Remove from oven and increase oven temperature to broil.
While the eggplant roasts, heat the remaining 1 tablespoon oil in a large skillet over medium-high heat. Add onion; cook, stirring often, until softened, 3 to 4 minutes. Add tomato paste, cumin, and garlic; cook, stirring constantly, until fragrant, about 1 minute. Add tomatoes, bell pepper and the reserved chopped eggplant; cook, stirring occasionally, until the eggplant is tender, 8 to 10 minutes. Remove from heat; stir in parsley, olives and vinegar.
Divide the filling evenly among the eggplant shells; top each with 3 tablespoons feta. Broil until the cheese is melted and golden, 6 to 8 minutes. Sprinkle with fresh oregano and dill, if desired.
