Preheat the grill or grill pan to medium-high. Place half the olive oil in a bowl and while the grill is heating, brush the cut sides of the romaine lettuce with the olive oil. Season the cut side generously with pepper and lightly with salt.Once grill pan is heated, place the sliced side down and let cook for about 5 minutes. Periodically, put medium pressure with a spatula on top to ensure the lettuce cooks. Repeat until all lettuce halves are cooked. Set aside.After two lettuce halves have cooked, in another skillet, add in the rest of the olive oil. Once oil heats, add in the onion noodles and season with salt, pepper and garlic powder. Cook for 5-7 minutes or until caramelized and lightly browned.Top the grilled lettuce with onions and blue cheese and drizzle with balsamic vinaigrette.