Combine vinegar, oil, and oregano. Coat cut sides of the eggplants with mixture and season with salt and pepper.
Preheat grill to high, then lower to medium after 15 minutes.
Arrange eggplants on grill, cut side down and grill for 5 minutes or until tender and lightly browned. Turn the eggplants over and lay a slice of provolone on each. Continue to grill 3 more minutes or until cheese begins to melt. Top eggplant with fresh tomatoes and chilies.