French Onion Soup

5 from 1 vote

Do not underestimate the glory that is French Onion Soup. Something magical happens when you combine the simple elements of this recipe: a killer savory beef broth, perfectly golden caramelized onions, and of course, enough toasty bread and melty cheese to make you weep. I've got details and photos to show you exactly how to make the best easy broth, caramelized (not burned) onions, and the method for broiling it all to perfection. A fun project for a rainy afternoon at home!

Prep Time10

Cook Time1 40

Total Time1 50

Course: Soup

Cuisine: French

Servings:

Calories: 405kcal

Author: The Food Charlatan

Ingredients

4 large yellow onions about 3 pounds, thinly sliced
4 tablespoons butter (half stick)
1 tablespoon kosher salt use less if you have table salt
1/4 teaspoon cayenne pepper optional, this adds flavor but no heat
2 tablespoons all purpose flour
1/2 cup sherry wine or white wine (I used cooking wine)
1 tablespoon fresh lemon juice about half a lemon
8 cups high quality beef broth I like Brodo brand, or Kettle and Fire
2 cups water
1 tablespoon Better Than Bouillon Beef Base
3 carrots peeled and roughly chopped
1 yellow onion roughly chopped
2 stalks celery roughly chopped
6 large cloves garlic smashed
1 teaspoon prepared horseradish or more if you like it a little spicy
3 sprigs fresh thyme 1/2 teaspoon dried thyme
3 small sprigs fresh rosemary 1/2 teaspoon dried rosemary
3 bay leaves
15 peppercorns about 1/2 teaspoon
1 (1-pound) loaf of French Bread sliced
1 cup gruyere cheese freshly grated
1 cup Parmesan cheese freshly grated
8 ounces Swiss cheese sliced

Instructions

Start by slicing up the onions. You want about 3 pounds of onions, which is usually about 4 large onions. See my How to Cut Onions post for details about how to stop from crying through this process! Slice the onions rather thin; it makes them easier to eat in the soup later. You should have about 8 cups of sliced onions.
Saute the onions. In a 12-inch, high sided stainless steel pan*, melt 4 tablespoons butter over medium heat. Add the onions all at once. Sprinkle the onions with 1 tablespoon kosher salt. (Use about half that amount if you only have table salt.) Add 1/8 or 1/4 teaspoon cayenne pepper.
Let the onions cook over medium heat for about 10 minutes, stirring occasionally, until they are transparent.
Turn the heat down to medium low. Let the onions cook for about 90 minutes. Yes, really! Check in every 10-20 minutes to give them a stir and make sure they are cooking evenly. See photos for an idea of what they look like through the whole process.
Make the broth in a separate pot. In a large dutch oven or stock pot set over high heat, add 10 cups high quality beef broth.*** Add 2 cups water. (I know this seems like a lot of liquid, but some of this will cook off.) Add 1 tablespoon Better Than Bouillon Beef Base.
Add the veggies to the broth. Add 3 carrots, peeled and roughly chopped. Add 1 onion, peeled and roughly chopped. Add 2 stalks of celery, roughly chopped. Smash 6 cloves of garlic with the side of a chef's knife and add them to the broth. Add 1 teaspoon prepared horseradish. Add 3 sprigs of fresh thyme (or 1/2 teaspoon dried thyme) and 3 small sprigs fresh rosemary (or 1/2 teaspoon dried rosemary.) Add 3 bay leaves and 15 peppercorns (about 1/2 teaspoon).
Once the broth mixture comes to a boil, lower the heat to a low simmer. Cover with a vented lid, allowing some steam to escape. Keep an eye on the heat and make sure it stays at a low bubble.
Let the broth simmer the entire time that you are caramelizing your onions. When the onions are finished caramelizing, drain the pot of broth through a colander into a large bowl. Add the broth back to the pot and keep warm. Discard the vegetables, but do eat the carrots at least (they are delicious).
Back to the pan with the caramelizing onions: The onions will slowly start to turn light yellow, then golden, then eventually a deeper golden. There is no need to caramelize onions to within an inch of their life. A deep golden shade across the entire pan of onions is all you need to get that sweet, umami flavor. The onions don't need to be a dark brown. Make sure you don't turn the heat up; that will just get you scorched edges, pulling in a bitter, acrid flavor that can take over the entire dish.
Taste the onions. This will give you a better idea than the color, even. They should be sweet, but with a deep, bold flavor. There should be none of that onion-y "bite." If they still taste rather flat, keep caramelizing until you get a more complex flavor.
When your onions have sufficiently caramelized, sprinkle them with 2 tablespoons flour and stir it together until the flour is incorporated, about 1-2 minutes.
Add 1/2 cup sherry wine (or white wine**) to the pan and turn the heat up to medium. Stir thoroughly and use a wooden spoon to scrape up the browned bits on the bottom of the pan.
Add the juice from a half a lemon, about 1 tablespoon, and continue stirring over medium heat until the liquid is mostly absorbed. The bottom of the pan should be smooth and cleared of any brown bits.
Scrape the caramelized onions into the pot of drained broth. Stir it together and taste your soup. Does it need salt? More horseradish? a pinch of extra thyme? Adjust to your liking.
Prepare the bread. Heat your oven to 350 degrees F. Slice your loaf of French bread into 1-inch slices. Lay the bread out on a baking sheet in a single layer. If you are feeling a little extra, you can butter each slice of bread with butter before toasting.
Toast the bread at 350 for about 10 minutes, or until the top is quite crisp. Flip each piece of bread over and continue toasting at 350 for another 5 minutes, until it's toasty on the other side.
Meanwhile, finely grate 1 cup parmesan cheese and 1 cup gruyere cheese. Sprinkle about 1/2 tablespoon of both cheeses in the bottom of 7 oven-safe serving bowls.****
Ladle the soup into the bowls. Set the bowls on a half baking sheet to use as a tray to get them in and out of the oven.
Top each bowl with a toasted slice of bread. Top with a sprinkle of 1/2 tablespoon each shredded gruyere and parmesan. Lay a slice of Swiss cheese on top.
Broil. Move the rack to the upper third of the oven. Place the baking sheet with the soup bowls in the oven. Turn the broiler up to high heat. Let broil for 2-4 minutes, until the cheese is melty and starting to get brown spots.
Remove the baking sheet from the oven. Use hot pads to transfer the bowls to the table, and remind your guests that the bowls are very hot!
Garnish each bowl with freshly chopped chives and cracked black pepper.
Storage: French onion soup is best kept in a container with an airtight lid in the refrigerator for about 4-5 days. Make sure to keep the leftover soup separate from the bread and cheese!
Freezing: You can totally freeze this soup! See post for details. Keep the bread and cheese separate!

Notes

*A stainless steel skillet will caramelize your onions faster and more effectively than an enamel lined pan. Cast iron would also work fine.

**I use cooking wine! Don't be mad at me 😂 I just don't keep wine in the house. Use whatever level of fancy wine you want!

***Beef Broth: The higher quality your beef broth is, the better. I bought a top-rated brand called Brodo on Amazon, and it was amazing. On another test, I use ONLY Better Than Bouillon Beef Base and water. I don't recommend this. This might be the one and only time! (I live by Better Than Bouillon.) But it was too salty and grainy, and the flavor wasn't rich enough.

I recommend buying the highest quality beef broth you can afford, and then in addition, adding water and a tablespoon of Beef base, as stated in the recipe, for an added boost of flavor.

****If you don't have oven safe bowls: No problem! Toast the bread on each side as described in the recipe. Once both sides are toasted, top each piece of bread with a little parmesan, gruyere, and lay a slice of Swiss cheese on top. Broil on the top rack for 1-3 minutes, until the cheese is melty. Ladle the soup into regular bowls, then top each bowl with a toasty cheesy bread.

Nutrition