The other day I bought one of those giant bags of Vidalia onions you see at Costco, because they looked to good to me and I needed lots of onions. I've been spending the last few weeks trying to figure out how to use them all. Fortunately, this recipe calls for a lot. This is really the best French Onion Soup I've made at home. What I like about the recipe is the clever way to carmelize onions in the oven. This technique was invented by the Americas Test Kitchen kitchen scientists (which totally rock!). Their technique allows you to set it and forget it for a while and then come in at the end and finish the soup off. The recipe is really good as long as you have a good rich beef broth. Best to make your own but store bought is ok. I highly recommend and this is truly a recipe you can keep. Enjoy!
- 3 tablespoons unsalted butter, cut into 6 pieces
- 6 large Vidalia onions (about 5 pounds), halved and cut pole to pole into generous ¼-inch-thick slices
- 1 teaspoon salt
- 2 cups water, plus about 1/2cup for deglazing
- ½ cup dry sherry or cooking sherry
- 3 cups low-sodium chicken broth
- 3 cups beef broth
- 4-6 sprigs fresh thyme, tied with kitchen twine (Do not overdo it here)
- 1 bay leaf
- ½ teaspoon sea salt
- Ground black pepper
- 1 small baguette or bread you can toast
- 8 ounces sliced Swiss or Gruyère cheese (about 2 cups)
- Adjust oven rack to lower middle position and heat oven to 400F degrees.
- Generously spray inside of heavy-bottomed large (at least 5-quart) Dutch oven with nonstick cooking spray.
- Place butter in pot, add onions and 1 teaspoon salt. Cook, covered, 1 hour (onions will be moist and slightly reduced in volume).
- Remove pot from oven and stir onions, scraping bottom and sides of pot. Return pot to oven with lid slightly ajar and continue to cook until onions are very soft and golden brown, 1½ to 1¾ hours longer, stirring onions and scraping bottom and sides of pot after 1 hour.
- Carefully remove pot from oven and place over medium-high heat. Using oven mitts to handle pot, cook onions, stirring frequently and scraping bottom and sides of pot, until liquid evaporates and onions brown, 15 to 20 minutes, reducing heat to medium if onions are browning too quickly.
- Continue to cook, stirring frequently, until pot bottom is coated with dark crust, 6 to 8 minutes, adjusting heat as necessary. (Scrape any fond that collects on spoon back into onions.)
- Stir in ¼ cup water, scraping pot bottom to loosen crust, and cook until water evaporates and pot bottom has formed another dark crust, 6 to 8 minutes. Repeat process of deglazing 2 or 3 more times, until onions are very dark brown.
- Stir in sherry and cook, stirring frequently, until sherry evaporates, about 5 minutes.
- Stir in broths, 2 cups water, thyme, bay leaf, and ½ teaspoon salt, scraping up any final bits of browned crust on bottom and sides of pot. Increase heat to high and barely bring to boil. Reduce heat to low, cover, and simmer 30 minutes.
- Remove and discard herbs, then season with salt and pepper. (most likely doesn't need any salt).
For the croutons:
- While soup simmers, arrange baguette or bread slices in single layer on baking sheet and bake in 400-degree oven until bread is dry, crisp, and golden at edges, about 10 minutes.
- Adjust oven rack 6 inches from broiler element and heat broiler. Set individual broiler-safe crocks on baking sheet and fill each with about 1¾ cups soup.
- Top each bowl with 1 or 2 baguette slices and layer with Gruyère.
- Broil until cheese is melted and bubbly around edges, 3 to 5 minutes. Let cool 5 minutes before serving.