French Onion Soup

French Onion Soup

As the story goes, King Louis XV of France returned late one night from a long (and we can assume, unsuccessful) day of hunting to find nothing in the larder at his lodge but onions, butter and champagne. Being the resourceful cook that he was— voila!—the first French Onion Soup.

Serves 6.
Tie the parsley and thyme sprigs together with kitchen twine so they will be easy to retrieve from the soup pot. Slicing the baguette on the bias will yield slices shaped to fill the mouths of the bowls.

Ingredients:

Soup
2 tablespoons unsalted butter
5 medium red onions (about 3 pounds), halved and sliced thin
Salt
6 cups low-sodium chicken broth
1 3/4 cups low-sodium beef broth
1/4 cup dry red wine
2 sprigs fresh parsley
1 sprig fresh thyme
1 bay leaf
1 tablespoon balsamic vinegar
Ground black pepper

Cheese-Topped Crusts
1 baguette, cut on the bias into ½-inch slices (2 slices per serving)
4½ ounces Swiss cheese, sliced 1/16 inch thick
1½ ounces Asiago cheese, grated (about 3/4 cup)

1. For the soup: Melt the butter in a large stockpot or Dutch oven over medium-high heat; add the sliced onions and 1/2 teaspoon salt and stir to coat the onions thoroughly with the butter. Cook, stirring frequently, until the onions are reduced and syrupy and the inside of the pot is coated with a very deep brown crust, 30 to 35 minutes. Stir in the chicken and beef broths, red wine, parsley, thyme, and bay leaf, scraping the pot bottom with a wooden spoon to loosen the browned bits, and bring to a simmer. Simmer to blend the flavors, about 20 minutes, and discard the herbs. Stir in the balsamic vinegar and season with salt and pepper. (The soup can be cooled to room temperature and refrigerated in an airtight container up to 2 days; return to a simmer before finishing the soup with the croutons and cheese.)

2. For the crusts: Adjust an oven rack to the upper-middle position and heat the oven to 350 degrees. Spread the bread out on a rimmed baking sheet and bake, flipping once, until lightly browned, about 15 minutes. Remove the bread from the oven. Turn the oven to broil.

3. Set heat-safe soup bowls or crocks on a rimmed baking sheet; fill each with about 1½ cups of the soup. Top each bowl with 2 toasted baguette slices and divide the Swiss cheese slices, placing them in a single layer, if possible, on the bread. Sprinkle each serving with about 2 tablespoons of the grated Asiago and broil until well browned and bubbly, 7 to 10 minutes. Cool 5 minutes and serve.