Sauté the onions in the olive oil in a big, heavy bottomed pan, over a medium high heat. Cook them for at least half an hour, until they are well browned but not burnt.
2 Add the sugar about 10 minutes after you start the process to help with the caramelizing.
3 Add the garlic and cook for a minute. Add the vermouth, wine or sherry, the dried thyme and the bay leaf you add the broth when you add the vermouth.
4 Cover the pan partially and let the French onion soup simmer for half an hour, to allow the flavors to blend.
5 Season with salt and pepper and discard the bay leaf.
6 Serve in bowl with toasted bread and slice of cheese.
