Sweet caramelized onions are the star of the classic French onion soup. This recipe shows you the best way to get the best flavour from your onions making the best soup! Topped with cheesy Gruyere cheese croutons, French onion soup can be served as an appetizer or a main meal.
French onion soup is an old school classic that we all know (and hopefully) love. You may have had a really great bowl of it somewhere, and chances are you've also had a lacklustre bowl of it too. The difference between a great bowl and a bland bowl? It's all in the onions and how they're cooked.
This recipe for French onion soup takes the time to properly caramelize the onions and bring out their natural sweetness.
Pro-tip - you should never have to add sugar to French onion soup.
Why you're going to love this
- Cozy comfort food - theres not much better than a big bowl of soup when you're looking for winter comfort food. Add in a cheesy crouton and we're headed for perfection.
- Simple ingredient list - the beauty of French onion soup is in the simplicity - just a few fresh ingredients and some time and you have a delicious soup.
- Perfect technique - you should never have to add sugar to your onions to highlight their sweetness, it's all there in the onion and it just takes time to bring out.
- Onions - I used plain old yellow onions, the kind you grab in a big bag. You can use any onion you like or even a combination.
- Butter - for cooking down the onions. You could use oil here as a substitute, but I prefer the flavour of butter on the onions.
- Beef stock - I use Better Than Boullion. Hands down it's the best beef stock I've found and the quality of the stock really matters here. The only thing better is beef stock made from scratch.
- Thyme and bay leave - to add some earthy flavour to the broth.
- Garlic - For garlic, fresh is always best. I used 3 cloves here but if you want a more pronounced garlic flavour add a couple more.
- White wine - Always choose a dry white wine. We use it here to deglaze the pot and to bring some acidity to the soup to balance the flavours. An alternative choice would be brandy or cognac.
- Flour - to thicken the broth.
- Bread (not pictured) - I love to use baguette here because a couple of slices fit nicely into the bowl.
- Olive oil (not pictured) - to get the croutons nice and crispy. You could use any oil here truly, but I love the flavour of olive oil in a crouton.
- Gruyere cheese - the nutty salty flavour of gruyere is such a nice contrast to the sweet onions. If you can't find it any other Swiss cheese will do.
How to make it
This soup takes a while to cook, but there are only two easy parts: caramelizing the onions, and then cooking the soup. The onions are what take the most time but please trust me that the end result is worth it. To properly caramelize onions you will need at least an hour of your time. I have seen recipes claiming to do it in half the time but it's just not possible and you will be sacrificing the flavour of the onions. In a soup that is primarily onions and broth, you want the flavour of both to be spot on.
Caramelizing the onions. Heat a 6 quart Dutch oven or similar sized heavy bottomed pot to medium heat and add the butter. When the butter melts add the onions. They should come up to almost the top of the pot but don't worry - they will reduce in size. Let the onions cook stirring every few minutes until they are a rich golden colour. As the onions begin to reduce you will most likely need to turn the temperature down a bit to keep them from burning. Plan on at least an hour for the onions to fully caramelize.
Add the garlic and deglaze the pot. When the onions have caramelized add the garlic and sauté for a couple of minutes before adding the wine. Increase the heat to medium and let the wine cook off until it reduces by half.
Add the flour. Add the flour to the onions and stir until it is mixed in well.
Finish the soup. Pour in the beef stock and place the thyme and bay leaves on the top. Increase the heat to high until the pot begins to boil then reduce to a low simmer and cover. Let the soup cook for 20-30 minutes then remove the thyme twigs and bay leaves from the pot.
Make the croutons. Slice the baguette into 8 slices about an inch thick then brush both sides with olive oil. Bake in the oven at 425ºF until they are golden brown then remove to cover in cheese before baking them again until the cheesy is melted.
Serve. Ladle the soup into bowls and top with the cheesy crouton. Alternatively, If you have oven-safe bowls you can add the croutons to the bowl before you top them with cheese. Once the crouton is in the bowl top with cheese and then place the whole bowl in the oven until the cheese melts.
Tips for the best French onion soup
Cut onions uniform and thin - thin uniform slices of onion will caramelize faster and at the same rate producing the most flavourful onions.
Take the time to properly caramelize - the bulk of the flavour in this soup comes from the caramelized onions. Take the time to do it right if you want the best flavour.
Do not add sugar - properly caramelized onions will bring enough sweetness to the soup. You should never need to add sugar to French onion soup.
Use a great stock - Two things flavour this soup: the onions and the stock. Using a great stock will bring you great flavour and your soup will fall flat if you don't.
Your onions don't need to be a deep brown colour - you can continue to caramelize them further than I do, but it's not necessary for the overall flavour of the dish.
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French Onion Soup
- 4 lbs onions
- 1⁄4 cup butter
- 2 bay leaf
- 6 cups beef stock
- 6 sprigs thyme
- 3 cloves garlic
- 3 Tbsp flour
- 1 cup dry white wine
- 8 slices baguette
- 1 Tablespoon olive oil
- 4 oz Gruyere - shredded
Caramelize the onions
- Place a 6 quart Dutch oven or similar sized heavy bottomed pot over medium heat and add the butter. When the butter melts add the thinly sliced onion to the pot. every five minutes or so check on the onions. Make sure they are not beginning to burn on the pot and give them a good stirring.As the time passes, the volume of the onions will begin to shrink and the onions will change in colour from white to a light golden or amber colour.
Make the soup
- Add the garlic to the onions and saute for a couple of minutes before adding the wine. Let the onions cook with the wine until it has reduced by at least half.
- Add the flour and stir well to coat the onions.
- Add the beef stock, bay leafs and thyme then bring the pot to a boil. Reduce the heat to low and let the pot simmer for 20-30 minutes.
Make the croutons
- Slice the baguette into thick slices then brush with olive oil on both sides before baking in the oven at 425ºF until golden brown.Spread out the shredded cheese over the croutons and place them back into the oven until the cheese melts.
- Ladle the soup into bowls and place the cheesy croutons on top.
* nutritional information is calculated by online tools and may not be 100% accurate.