Classic French Onion Soup

Picture yourself walking around Paris, taking in all the sights and sounds of the city.  You start to get tired so you walk into a nearby cafe or brasserie – one of the ones with small tables and chairs squeezed together all facing the street.  You sit down, and what’s the first thing you order?

Building reflections in the Canal St. Martin in Paris, France
Le Canal St. Martin – Paris, France

I have a few top contenders 🙂  One- a croque madame sandwich with melted cheese and a fried egg.  Two- a big salad with French ham and lots of emmentaler cheese.  Three- classic French onion soup.  Ohh, classic French onion soup.

There really is nothing better than walking into a bistro and confidently ordering a soupe à l’oignon gratinée, and then being met with a steaming bowl of caramelized onion and melted cheese heaven.

Classic French Onion Soup

Classic French onion soup is all about the simplicity of a few ingredients and lots of time.  It can be soul satisfyingly wonderful, but it can also be kind of bad if any of the ingredients are off.  With that in mind, I give two pieces of advice prior to making this French bistro classic:

  1. Take the time to truly caramelize your onions.  This will take time (1 hour minimum), but is oh so worth it.
  2. Use good quality broth and/or stock – and it doesn’t have to be all beef!  If you have homemade stock, now is the time to use it.

Classic French Onion Soup

Classic French Onion Soup

Here’s what you’ll need:

For the Soup

  • 6 large yellow onions
    • Sliced ⅛ inch thick
  • 6 tbsp unsalted butter, divided
  • ¼ tsp kosher salt
  • 2 tbsp all purpose flour
  • 500 ml dry white wine
  • 1 parmesan rind, optional
  • 1 bay leaf
  • 1 bunch fresh thyme leaves
  • 4 cups beef broth (32 oz)
  • 5 cups homemade chicken stock
  • Splash dry sherry, optional
  • Kosher salt and black pepper to taste

For the Extras

  • 1 loaf crusty bread – a French baguette or a rustic Italian loaf both work well
  • 2 cups shredded gruyere
  • 1 cup shredded parmesan cheese
  • 2 tsp chopped thyme

Yellow Onions and Bay Leaf for Classic French Onion Soup

You start where all classic French onion soup starts:  with the onions.  This part is a pain, not gonna lie about that.  Remove the skins from the onions and slice them very thinly, about 1/8 inch thick.  A mandoline makes this so much easier and makes the size of your onion slices a lot more consistent, but it’s not a necessity.

I like to use yellow onions for the soup, but sweet onions or white onions would work as well.

Caramelizing onions for Classic French Onion Soup
Onions before any cooking

Now you start the caramelization process.  The goal of this is to draw out the sugars slowly so they cook evenly and don’t burn.  You can certainly achieve browned onions quickly, but they’ll be bitter (have you ever eaten burnt sugar?  It’s that taste.) and won’t have a deep, even flavor that true caramelized onions have.

Melt 4 tbsp butter in a large dutch oven over medium heat, add your onions and kosher salt to the pot (they will likely just barely fit), and cover for 5 minutes.  The picture above shows the beginning of this process.

Caramelizing onions for Classic French Onion Soup
Onions after 10 minutes covered over medium heat

After 5 minutes of covered cooking over medium heat, remove the lid and stir the onions so the bottom layer doesn’t start to brown.  Place the lid back on and cook for an additional 5 minutes.

This 10 minutes of cooking over medium heat while covered helps to speed up the initial cooking process.  The steam and higher heat soften all the onions and helps them create moisture.  It’s the only “shortcut” you want to take when making caramelized onions.

Caramelizing onions for Classic French Onion Soup
Onions after 30 minutes of total cooking

Reduce the heat to low and remove the lid.  Continue to cook over low heat stirring occasionally.  You don’t have to pay too much attention to the onions at this point.  So tidy up the kitchen a bit and get the rest of your ingredients in order.

This feels like the most tedious part of the process.  You have a good 30-40 minutes where you’re thinking are these onions ever going to change color??.

Caramelizing onions for Classic French Onion Soup
Onions after 40 minutes of overall cooking

After about 40 minutes, you’ll start to see some golden browning action.  If you notice the onions getting dried out or the bottom of the pan darkening too much, you can add a splash of water to loosen things up.  Keep a closer eye on the onions now so they don’t burn.

Keep going, you’re getting closer!

Caramelizing onions for Classic French Onion Soup
Onions after 75 minutes of total cooking

After 1 hour and 15 minutes your onions will have developed a deep golden color and almost jammy consistency.  If yours don’t then keep going a little bit longer.  Once they do, add the remaining 2 tbsp butter to the pan plus the flour.  Cook over low heat for 3-5 minutes to cook out the raw flour taste.

The flour helps give just a little bit of body to the soup.  It’s not enough to make it creamy but is just enough to give it that extra something.

Caramelizing onions for Classic French Onion Soup

Now you deglaze the pan to get all those caramelized bits incorporated into your soup.  Add the dry white wine to the onions and cook over medium heat for 2-3 minutes, just long enough for the alcohol in the wine to cook off.

You want to make sure to use a good quality wine here, if you wouldn’t drink it don’t cook with it.  I usually aim for something not too expensive but that I’d happily pour myself a glass of if I was sitting down to drinks with friends.

Caramelized Onions with Bay Leaf, Thyme and Parmesan Rind for Classic French Onion Soup

Now add your secret ingredients:  parmesan rind, bay leaf, and fresh thyme.  I keep a ziploc bag of parmesan rinds in my freezer for exactly occasions like these, though you can buy them at the store now as well.

Next add the beef broth and homemade chicken stock.  I like the balance that using both beef and chicken broth gives, and sometimes I find all beef French onion soup to be overpowering.  Feel free to adjust the ratios to your liking, but I highly suggest using homemade stock if you have it or making sure what you’re buying is good quality and low sodium.

Real Simple has a good guide to the best broths and stocks of each category that’s worth checking out!

Classic French Onion Soup

Bring the soup to a boil, then reduce the heat to low, cover, and simmer for 20-30 minutes.  The onions should be very soft and the broth flavorful.  Season with salt and pepper to taste.  The amount of salt you need will depend on the saltiness of your broths, so trust your own judgement here and go with what tastes best.

Add a splash of dry sherry, if you have some available.  I always struggle with buying something so expensive for a small splash, so I usually omit this.  But it does give it a little extra something.  Serious Eats suggests fish sauce and/or apple cider vinegar, and I didn’t hate either of those additions!Croutons for Classic French Onion Soup

Discard the parmesan rind, bay leaf, and thyme, and your soup is done!  You could easily service this as is with some bread and cheese to dip on the side, but if you want to go for real classic French onion soup you have to do the obligatory broil in the oven.  The trick here is you need oven proof bowls, crocks, or mugs to be able to cook in.  Check the bottom of some of your dishes, you might be pleasantly surprised to find out which are oven safe.

Cube your loaf of bread and toast in an oven at 425 for 10-12 minutes.  You have some creative license with the bread – for example, I used a roasted garlic loaf I found at the grocery store and it was lovely.  Next, shred your cheese and get ready to assemble.

The best French onion soup layering technique goes like this:  fill the bowl halfway with soup –> add a layer of bread cubes –> add a layer of cheese –> ladle more soup over top –> add another layer of bread cubes –> finish with a final layer of cheese and some fresh thyme leaves on top.

This recipe makes enough for about 6 bowls of soup.  Only cook the soup you plan to serve immediately and save any leftover without the cheese and bread for up to 3-4 days.

Crocks of Classic French Onion Soup Ready for the Oven

Preheat the oven to 425, place the oven safe dishes on a baking sheet for easier transport, and put them in the top rack of the oven for 10-15 minutes or until the tops are golden, crispy, and bubbly.

Let the dishes cool for a few minutes prior to serving, and don’t forget to warn everyone that the dishes are very hot!

Classic French Onion Soup

 Bon appétit!

Classic French Onion Soup

A bistro favorite, this classic French onion soup is both simple and satisfying with rich, caramelized onion flavor throughout

Course Soup
Cuisine French
Prep Time 10 minutes
Cook Time 1 hour 45 minutes
Total Time 1 hour 55 minutes
Servings 6

Ingredients

For the Soup

  • 6 large yellow onions sliced 1/8 inch thick
  • 6 tbsp unsalted butter divided
  • ¼ tsp kosher salt
  • 2 tbsp all purpose flour
  • 500 ml dry white wine
  • 1 parmesan rind optional
  • 1 bay leaf
  • 1 bunch fresh thyme leaves
  • 4 cups beef broth
  • 5 cups homemade chicken stock
  • Splash dry sherry optional
  • Kosher salt and black pepper to taste

For the Extras

  • 1 loaf crusty bread
  • 2 cups shredded gruyere
  • 1 cup shredded parmesan cheese
  • 2 tsp chopped thyme

Instructions

  1. Remove the skins from the onions and slice them very thinly, about 1/8 inch thick

  2. Melt 4 tbsp butter in a large dutch oven over medium heat, add your onions and kosher salt to the pot, and cover for 5 minutes.

  3. After 5 minutes of covered cooking over medium heat, remove the lid and stir the onions so the bottom layer doesn't start to brown. Place the lid back on and cook for an additional 5 minutes.
  4. Reduce the heat to low and remove the lid. Continue to cook over low heat stirring occasionally

  5. After about 40 minutes, you'll start to see some golden browning action. If you notice the onions getting dried out or the bottom of the pan darkening too much, you can add a splash of water to loosen things up. Keep a closer eye on the onions now so they don't burn.
  6. After 1 hour and 15 minutes your onions will have developed a deep golden color and almost jammy consistency. If yours don't then keep going a little bit longer. 

  7. Once they've reached a deep golden brown, add the remaining 2 tbsp butter to the pan plus the flour. Cook over low heat for 3-5 minutes to cook out the raw flour taste.

  8. Deglaze the pan with the dry white wine and cook over medium heat for 2-3 minutes, just long enough for the alcohol in the wine to cook off.

  9. Add parmesan rind, bay leaf, fresh thyme, beef broth, and homemade chicken stock to the pot and bring to a boil

  10. Reduce the heat to low, cover, and simmer for 20-30 minutes. The onions should be very soft and the broth flavorful. Season with salt and pepper to taste.

  11. Add a splash of dry sherry, if you have some available.
  12. Discard the parmesan rind, bay leaf, and thyme, and your soup is done!
  13. Cube your loaf of bread and toast in an oven at 425 for 10-12 minutes.
  14. Shred your cheese and get ready to assemble.

  15. Fill oven safe bowls halfway with soup --> add a layer of bread cubes --> add a layer of cheese --> ladle more soup over top --> add another layer of bread cubes --> finish with a final layer of cheese and some fresh thyme leaves on top.

  16. This recipe makes enough for about 6 bowls of soup. Only cook the soup you plan to serve immediately and save any leftover without the cheese and bread for up to 3-4 days.
  17. Preheat the oven to 425, place the oven safe dishes on a baking sheet for easier transport, and put them in the top rack of the oven for 10-15 minutes or until the tops are golden, crispy, and bubbly.
  18. Let the dishes cool for a few minutes prior to serving, and don't forget to warn everyone that the dishes are very hot!



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