Preheat oven to 375 F. Remove stems. Cut a lengthwise slit down the center of each eggplant; do not cut in half. Pry open to expose inner flesh. Salt each to taste, then brush all over with olive oil. Place in a lightly oiled pan and roast until soft, about 20 minutes. Meanwhile, sauté onions and garlic in oil until soft. Add parsley, oregano, tomatoes, salt, pepper, and sugar. Bring to a boil, reduce heat, and simmer for 15 to 20 minutes. Remove eggplants from oven and spoon sauce into each slit. Pour remaining sauce around eggplants. Swirl olive oil over all and continue baking until eggplants are very soft and a bit charred, about 30 to 40 minutes. Serve with crusty bread, a green salad, and a side of sliced feta cheese. Serves six.