Quick Red Onion Soup Gratinée

Soup Base

1. 1In a large pot or Dutch oven, melt butter over medium heat. Add the sliced red onions and cook, stirring occasionally, until softened and lightly caramelized, about 10-15 minutes.
2. 2Add minced garlic and cook for 1 minute more until fragrant.
3. 3Sprinkle the flour over the onions and stir to coat. Cook for 1 minute, stirring constantly.
4. 4Gradually whisk in the chicken broth. Add balsamic vinegar and dried thyme. Bring to a simmer.
5. 5Reduce heat to low, cover, and let simmer for at least 30 minutes to allow flavors to meld. Season with salt and pepper to taste.

Gratinée

1. 1Preheat your broiler.
2. 2Toast the sourdough bread slices until golden brown on both sides. This can be done in a toaster, under the broiler, or in a dry skillet.
3. 3Ladle the hot soup into oven-safe bowls.
4. 4Place one slice of toasted sourdough bread on top of the soup in each bowl.
5. 5Generously sprinkle the shredded provolone cheese over the bread, ensuring it covers the edges.
6. 6Carefully place the bowls on a baking sheet and broil for 2-3 minutes, or until the cheese is melted, bubbly, and lightly golden brown. Watch closely to prevent burning.