This French onion soup with kale is hearty and loaded with rich caramelized onion flavor. It’s made with onions (lots of them), fresh kale, beef broth, olive oil, garlic, a bay leaf, apple cider vinegar, and balsamic vinegar. Plus, it’s topped with crusty bread and melted Emmental cheese.
All about this delicious French onion soup with kale
Guys, if I had to eat soup every day for the rest of my life, I would choose this soup. It is so good. ♡
It’s loaded with caramelized onion flavor, that’s accentuated by apple cider vinegar and a splash of balsamic vinegar. The addition of these two vinegars takes this French onion soup to the next level. They add brightness and give a subtle zing that perfectly balances the sweetness of the caramelized onion and the savory beef broth.
The addition of chopped kale makes this soup extra hearty and healthy. The roughly chopped kale is stirred into the caramelized onions (before the broth is added) and becomes coated with onion flavor which carries through with every bite, even once the other ingredients are added.
What you’ll need to make French onion soup with kale
- Olive oil
- Medium yellow onions (8)
- Garlic clove
- Fresh kale leaves
- Beef broth
- Apple cider vinegar
- Balsamic vinegar
- Bay leaf
- Kosher salt and ground pepper
- Plus, crusty baguette and Emmental cheese to top the soup before serving.
Let’s cook! How to make French onion soup
Making French onion soup isn’t complicated, but it does require a fair amount of chopping. If you are sensitive to onions (like me), grab goggles (swim or ski) beforehand. You will be glad you did. And yes, kids will think this is hilarious.
How to chop onions for this soup recipe
- Begin by removing both ends of the onion.
- Stand the onion on the board, cut side down.
- Slice the onion in half from the top down and remove the outer peel.
- Turn each half over, with the outside of the onion facing up.
- Cut the onion into 1/8 of an inch thick slices.
- Rotate your knife to cut the slices into smaller 1/2 inch bites. * Not necessary, but I find it much easier for kids to eat this soup when the onions are chopped smaller and not left in long slices.
Making French onion soup
- In a large 5-quart pot, add olive oil and heat over medium. Add the chopped onions and stir to coat them in the oil. Let them cook for 2-3 minutes before stirring with a wooden spoon. They will become translucent and tender.
- When stirring, be sure to scrape off and incorporate the brown bits from the bottom of the pot. You can add small splashes of water (a tablespoon at a time) to the pot to help break down/scrape off the browned bits. Reduce the heat if the onions start to burn. Continue this process for 15-20 minutes, until the onions are a deep caramel shade of brown and full of flavor.
- Add the salt, pepper, minced garlic, and roughly chopped kale to the onions. Stir until well combined.
- Add the remaining ingredients—broth, bay leaf, apple cider vinegar, and balsamic vinegar—and bring to a gentle boil. Let simmer for 10 minutes. Taste and add salt and pepper as desired.
How to serve French onion soup
This soup is delicious without crusty baguette and gooey melted cheese…but it’s extra tasty with these rich additions. I just don’t have the willpower to say no to bread and cheese…🤷♀️
- To serve, ladle the soup into an oven-safe bowl and top with a 1/2-inch slice of toasted baguette or a rustic country loaf.
- Place a thick slice of Emmental cheese over top and carefully place in the oven with the broiler on. Let the cheese melt and remove once it begins to bubble and brown.
- Careful when serving—the bowl will be hot!
- Other cheeses that work well: Gruyere, Gouda, or Mozzarella.
All those melty cheesy bites. I swoon. ♡
If you give this French onion soup recipe a try, let me know in the comments below. I love to hear from you!
Looking for delicious soup ideas? Check out some of our favorites!
French Onion Soup with Kale
- 8 medium yellow onions peeled, sliced, and chopped
- 4 tbsp olive oil
- 1 large garlic clove minced
- 1 bunch of kale ~ 5-6 large leaves, washed, destemmed, and finely chopped into small bites
- 1 tsp kosher salt
- 1/2 tsp freshly ground pepper
- 6 cups beef broth 1.5 cartons
- 1 bay leaf
- 1 tbsp apple cider vinegar
- 1 tsp balsamic vinegar
- sliced French baguette toasted
- sliced Emmental cheese
- In a large 5-quart stovetop pot, add olive oil and heat over medium heat. Add chopped onions and stir to coat them in the oil. Let them cook for 2-3 minutes before stirring with a wooden spoon. They will become translucent and tender. When stirring, be sure to scrape off and incorporate the brown bits from the bottom of the pot. You can add small splashes of water (a tablespoon at a time) to the pot to help break down/scrape off the browned bits. *Reduce the heat if you notice burning. Continue this process for 15-20 minutes, until the onions are a deep caramel shade of brown and full of flavor.
- Stir in garlic, kosher salt, and pepper. Add chopped kale and stir well to ensure the kale is coated.
- Add broth, vinegars, and the bay leaf. Bring to a slow boil and let simmer for 10 minutes.
- Taste and season with additional salt and pepper as desired. Ladle into an oven-safe bowl and top with a slice of crusty, toasted bread and sliced Emmental. Place in the oven under the broiler for 1-2 minutes, until melted and bubbling. Carefully remove, grab a spoon, and dig in!