I used to always make this from scratch but then we tried Campbell's onion soup and thought it wasn't bad really and when you add toasted garlic bread smothered with gruyere and broiled, it's great. I always have garlic bread frozen from leftover baguettes and usually have the cheese. I heat the soup first before putting it under the broiler. Also, I cut down the amount of water (use 2/3 of a can) and add a bit of sherry.
You really don't need anything else for lunch.