Traditional French Onion Soup

It's a gray day here in Atlanta and the thought of a proper onion soup will not vacate.
Luckily I have all the ingredients. A lot of recipes for onion soup call for broth
but traditionally it is made with just onions and water. It is a peasant dish after all.
Here is my recipe(Today I am actually only going to make a half recipe). I like  the little
hint of herbs that the thyme brings but it is not traditional that I know of. As always,
do what you like and tastes good to you. I wouldn't make a special trip to the market for
thyme but I have a garden full of it. The key here is to make sure you fully cook down the onions
until they are a rich golden brown. You cannot rush this process with high heat...trust me.
Go very slowly.

2 tablespoons butter
7 or 8 Yellow or Red onions (7 to 8 pounds), thinly sliced
Kosher salt
Freshly ground black pepper
3 or 4 springs fresh thyme (optional)
6 to 12 slices of baguette or any country-style bread
1/3 cup sherry
Red or white wine vinegar (optional)
Red wine (optional)
1/2 to 3/4 pound Gruyère or Emmanthaler cheese, grated ( It is important that you use one of these two cheeses and not some generic "Swiss" cheese....trust me.)

In a large pot, with a capacity of about 7 1/2 quarts...there are a lot of onions to start out with.
An enameled cast-iron pot is ideal. Start the onions and butter over medium heat.
Sprinkle with 2 teaspoons salt, cover, and cook until the onions have heated through and
begun to steam. At this point we want to lose moisture so uncover, reduce the heat to low, and cook,
stirring occasionally. When the onions have completely cooked down, the water has cooked off, and the onions have turned a rich brown (think maple syrup)(this will take a couple of hours) add 6 cups of water and season with several grinds of pepper and the thyme if you are using it. Raise the heat to high and bring the soup to a simmer,then reduce the heat to low. Simmer for 20 minutes to give the water time to extract the caramel from the onions. Add the sherry.

Taste and season with salt and pepper as needed. If the soup is too sweet, add some vinegar.
If you would like another dimension to the soup add a splash of red wine. (I do)

This is the the onion-to-liquid ratio that I like but it is OK to make it a little more delicate if you prefer by adding an additional cup of water or so.

Sometime while the onions are cooking down you need to place the sliced baguette in a 200F oven and let it dry out completely... 30 to 45 minutes.

When you are ready to serve, preheat the broiler and ladle the soup into bowls, float the dried bread
on top cover generously with the grated cheese. put the boils under the broiler until the cheese is melted and nicely browned. Serve immediately.

Serves 4 to 6