Preheat the grill to medium.
Slice a thin piece (1/16 inch) off the core end of each romaine, just to clean it up. Then cut lengthwise down the middle of each romaine heart, making 2 equal halves.
Brush both sides of each half lightly with olive oil and place cut side down on the grill. Grill only a couple of minutes, just until the leaves begin to wilt. Flip and repeat.
Remove from the grill and place cut side up on the plate. Sprinkle about a tablespoon of balsamic vinegar on each half, then drizzle with olive oil.
Add the bacon and tomatoes, and then top with cheese and season to taste with salt and pepper. Add the garlic croutons.