French Onion Soup

There are few soups quite like the sweet, umami delight that is a well made deep and delicious French onion soup. Learn how to get the most flavour out of the humble onion with my classic onion soup recipe with a little twist.

I can polish off a bowl of onion soup in the blink of an eye, I love it so much. The humble onion is elevated into new highs with this classic French recipe. The dark, rich soup that has so much flavour - deep and savoury, it's one of life's great treats.

I always order onion soup in a calssic French restaurant and invariably burn every part of my mouth and face trying to guzzle the soup too quickly. The island of cheese on top is another savoury delight - salty and melty. It really is too much! Cooking this soup in the midst of a cold spell outside is something I do annually, but I don't just reserve for the cold months - I can eat French onion soup any time of the year! The great news is that it's not difficult to make at home, all that's needed is a little patience.

What's Ahead?

What is French onion soup all about?

French onion soup is a savoury soup made primarily from onions, beef broth, and often served with croutons or a slice of bread topped with melted cheese. It's a classic French dish known for its rich, flavourful broth and caramelised onions. The onions are typically cooked slowly until they caramelise, which brings out their natural sweetness and depth of flavour.

The broth is made from beef stock or broth, which is simmered with the onions to develop a robust flavour. The soup is often served in individual crocks or bowls, topped with toasted bread or croutons and melted cheese, such as Gruyère or Swiss. It's then usually grilled until the cheese is melted and bubbly, creating a deliciously satisfying and comforting dish.

Why it works?

When cooked low and slow, onions take on an amazing umami sweetness that's something very special. A rich, creamy and decadent soup like no other. And it's such a humble dish too - few ingredients but BIG on flavour.

Stuff You'll Need

There's not a lot to making this soup, here's where the key flavours come from.

• Onions - I generally go for a large, sweet onion like a Vidalia or Walla Walla but generally, any yellow onion will do. On occasion I'll make it with red onion, as they're typically sweeter, but they're not strictly traditional for the French recipe. That said, use whatever you have!
• Butter - I fry the onions in butter as it has more flavour than oil.
• Herbs - Thyme and bay leaf will add all the floral undertones I like.
• Garlic - for a little backbone to the soup.
• Beef or Chicken stock/broth - I use both. Beef stock will give a more pungent flavour to chicken, but either is fine.
• Dark soy sauce - not traditional by any stretch, but soy sauce has a tonne of umami and also a great colour that enhances the soup. You don't taste it in the final dish, but it definitely brings something to the soup.
• Salt & pepper - essential to enhancing and rounding out the flavour.
• Bread & Cheese - A crusty slice of bread or large croutons topped with gruyere cheese is essential to any French onion soup.

Step by Step

Making the soup isn't difficult, here's how it's done.

1. Step 1 - In a large pan, heat the butter until it begins to bubble over a medium/high heat. Add the onion, thyme, and bay leaf, stirring well. Reduce the heat to medium/low and let them gently fry for 30 minutes, stirring regularly, until they soften and turn golden brown.
2. Step 2 - Add the garlic and fry for 1-2 minutes before introducing the stock and soy sauce (if using). Season with salt & pepper.
3. Step 3 - Bring the soup to a boil, then reduce the heat to low and simmer gently, uncovered, for 30-40 minutes, maintaining a gentle bubble.
4. Step 4 - Remove the bay leaf and any thyme stalks, then take the pan off the heat. Preheat a grill/broiler until it is hot. Lightly toast the bread in a toaster.
5. Step 5 - Meanwhile, ladle a portion of soup into a small bowl and place a slice of toast on top. Sprinkle about 1/2 cup of cheese over the bread, then place it under the hot grill/broiler for 3-4 minutes until the cheese is completely melted and bubbling. Repeat the process with more soup/bread/cheese. Serve hot!

Pro Tips

• Low and slow - We cook the onion down slowly. This will ensure a great texture, colour and flavour - 30 minutes of slow sautéing will get the job done. I like to fry the onions in a little butter (because France) and inject a little herbal delight in the form of fresh thyme and a bay leaf.
• Soy sauce - Now, this is probably going to fill my French readers with horror, but I do like to add a little dark soy sauce to my soup - so, before you leave in protest, hear me out! Soy sauce has a wonderful deep, rich colour which gives the soup a great deep hue, but also a rich, umami saltiness which adds a layer of flavour to the broth. I add around 1-2 tsp. It's obviously not traditional, but it works! It's also optional so don't sweat it if you're too horrified.
• Bread & Cheese - A good French Onion Soup Recipe isn't complete without the croutons to end all croutons. And by that I mean a slice of crusty bread toast with bubbling-hot Gruyère or Comté cheese on top. The cheese melts into the soup and the whole thing is an utter 'Triomphe!'.

Serving & Storage Suggestions

You can make the soup a few days in advance, in fact the flavour will only improve over time. Keep it well sealed in. the fridge until you're ready and reheat until piping hot and follow the recipe ofr adding cheese and bread to the bowls.

• Leftovers - Leftover soup will stay good in the fridge for up to a week.
• Freezing - Freeze the soup in single portions (without the cheese and bread) for 3+ months. Cook from frozen in the microwave until piping hot then finish off under a broiler in a bowl/crock with the bread and cheese as normal.

Ready to get cooking?

French onion soup is a great lunch or dinner dish - filling, rich and completely delicious. Great in cold weather, hot weather, wet weather, dry weather. You get the picture. It's one of my most favourite soups to eat. Hope you enjoy the recipe!

More delicious French recipes

If you liked this recipe for classic French onion soup, I'm sure you'll love some more of my favourite French recipes (and cocktails!).

• Salt Pork with Puy Lentils (Petit Sale aux Lentilles)
• Crab Croquettes
• Tomato & Feta Salad
• Anchovy Sauce
• Rabbit Liver Pâté with Slow Onions
• Asparagus with Dijon Mustard

Cocktails

• Pamplemousse Cocktail
• Picon Punch Cocktail
• Lucien Gaudin Cocktail

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