Whisk together vinegar, soy sauce, hoisin sauce (if using), sesame oil, sugar, ginger and garlic in a small bowl. Brush oil over all surfaces of eggplant and sprinkle with salt and pepper to taste.
Prepare barbecue grill (medium heat). Place eggplant, cut side down, on grill and let cook 5 minutes. Turn eggplant and brush with glaze; continue cooking until eggplant is very soft.
Transfer eggplant to serving platter and drizzle with more glaze. Sprinkle with minced scallions and serve.
Servings: