Step 1

Heat a large Dutch oven or heavy pot with the olive oil over medium heat. Add the onions, water, and salt and mix to coat. Cover with the lid and cook for 15 minutes.

Step 2

Remove the lid and add the butter and continue to cook, stirring occasionally. Keep an eye on the onions and adjust the heat to avoid burning. Add a splash of water every so often to avoid burning if necessary. Full caramelization where the onions become deep brown and sweet will take about 60-90 minutes longer.

Step 3

Once the onions are deeply caramelized add the garlic and cook for 1-2 minutes or until fragrant. Add the tomato paste and cook stirring frequently for 5 minutes. If the paste begins to burn, just add a splash of water.

Step 4

Add the flour to the pot and cook for 2 minutes or until all of the flour is no longer white.

Step 5

Add the vermouth or wine and bring to a boil while scraping the bottom of the pan with a wooden spoon to dislodge all of the brown bits.

Step 6

Once boiling add the beef stock and thyme and bring to a simmer. Cook at a simmer for at least 20 minutes.

Step 7

Taste test and adjust salt and pepper to taste. Add the brandy or sherry (optional) and stir to combine. At this point, the soup is done and can be placed into crocks or stored overnight for even more flavor.

Step 8

Turn the broiler to high and set the rack so that a sheet pan with soup bowls can fit.

Step 9

Ladle the soup into oven-safe soup crocks, leaving enough room for the bread and cheese. Place the crocks onto a baking sheet and place 2 pieces of bread or enough to roughly fit 1 layer on top of each bowl. Sprinkle the Gruyere, dividing evenly into each bowl.

Step 10

Broil for 2-3 minutes or until the cheese is bubbly and browned. Garnish with thyme leaves and serve. Enjoy!