Preheat grill for medium heat. While grill is heating, wash the eggplant and cut into 1/2-inch rounds, or cut length-wise if desired, also into 1/2-inch thick slices.
In a small bowl, whisk together the remaining ingredients: the olive oil, balsamic vinegar, garlic powder, salt and pepper. Brush the eggplant rounds on both sides with the mixture. Set aside any remaining marinade.
Grill eggplant slices a few minutes, rotate 45 degrees, grill another few minutes to get nice criss-cross grill marks. Flip eggplant slices over and repeat process on the other side.
This recipe works (and tastes) great with zucchini, asparagus, onion slices and other quick-cooking, grill-friendly veggies!