Preheat your oven's broiler. Cover a broiler pan or baking sheet with aluminum foil, and coat with non-stick cooking spray.
Arrange tomato slices in a single layer on the prepared baking sheet. Drizzle each slice lightly with olive oil, spreading oil evenly with finger if necessary. Season with salt, pepper, garlic, monosodium glutamate (if using), and oregano. Sprinkle Parmesan cheese over the top.
Broil, 3 inches from the heat until cheese is browned and bubbly, 3 minutes.
