French Onion Soup

Ingredients

• 4 largeonions, thinly sliced
• 960 ml (4 cups)beef broth
• 28 g (2 tbsp)butter
• 100 g (1 cup)grated Gruyère cheese
• 5 ml (1 tsp)sugar
• 5 ml (1 tsp)salt
• 5 ml (1 tsp)pepper
• 4 slicesFrench bread, toasted

Instructions

1. 1

   Cook the onions

   Melt the butter in a large pot over medium heat. Add the onions and cook for about 25 minutes, until caramelised.

2. 2

   Season the onions

   Add the sugar, salt and pepper, then stir well to combine.

3. 3

   Simmer the soup

   Pour in the beef broth and bring it to a boil. Lower the heat and simmer for 30 minutes.

4. 4

   Top the bowls

   Preheat the oven to the grill setting. Ladle the soup into oven-safe bowls, then top each with a toasted bread slice and grated Gruyère.

5. 5

   Melt the cheese

   Grill for 3–5 minutes, until the cheese has melted and is bubbling. Serve hot.

What is French onion soup?

French onion soup is a classic French dish built around onions cooked until deeply golden, then simmered in broth. It is often associated with French cafés and bistro cooking, where a simple bowl is made hearty with bread and melted cheese.

This version keeps the method straightforward: butter softens and browns the onions, while Gruyère and toasted French bread make a savoury topping.

Nutrition and macros by portion

The nutrition label shows one serving as written: 300 calories, 15g protein, 30g carbs, 15g fat.

The onions and bread provide most of the carbohydrates, while the butter and Gruyère contribute much of the fat. Beef broth and Gruyère provide protein. Pair a bowl with a crisp salad or other vegetables for a more balanced plate.

Build flavour with the onions

Onions: Slice them thinly so they soften evenly. Cook over medium heat for the full 25 minutes, stirring as needed to prevent sticking and help them colour consistently.

Butter: It provides the cooking fat and a rounded flavour. Keep the heat moderate; the onions need time to caramelise rather than scorch.

Season before adding broth

Sugar, salt and pepper: Stir these through the caramelised onions before adding the broth, as directed. This gives the seasoning a chance to coat the onions.

Broth: Bring it to a boil, then reduce the heat for a 30-minute simmer. A gentler simmer lets the onion flavour infuse the liquid without rapidly boiling it away.

Get the topping ready

Bread: Use toasted slices so they are ready to sit on top of the soup in the bowls. Their firm surface holds up better beneath the cheese than untoasted bread.

Gruyère: Grate the cheese so it melts across the bread. Put the bowls on a sturdy tray if that makes them easier to move to and from the grill.

Watch the final grill

Cheese: Grill the topped bowls for 3–5 minutes, keeping an eye on them as the cheese can go from melted to over-browned quickly. The recipe’s cue is melted, bubbling cheese.

Serving: Take care when handling the bowls, which will be hot. Serve the soup straight away while the topping is still soft and bubbling.

What to serve with it

The bread and cheese already make each bowl substantial. For a lighter contrast, serve it with a crisp green salad dressed simply with vinegar or lemon.

If serving it as part of a larger meal, offer smaller bowls before a simple main course rather than adding more bread to the soup.

Recipe notes & tips

• Slice the onions evenly so they cook at a similar rate.
• Use a large pot so the onions have room to cook without crowding.
• Let the onions take the full 25 minutes to caramelise rather than turning up the heat to hurry them.
• Toast the bread before assembling the bowls, as the method specifies.
• Check the bowls frequently during the 3–5-minute grilling time.
• Use oven-safe bowls for the final step.

Variations

• Use vegetable broth: Swap it for the beef broth for a meat-free version.
• Try another melting cheese: Use a similar amount of another cheese that melts well.
• Add fresh herbs: Finish each bowl with chopped thyme or parsley.
• Make smaller servings: Divide the soup among more oven-safe bowls and adjust the topping accordingly.
• Serve without grilling: Add the toasted bread and cheese at the table if you do not have oven-safe bowls.

Common mistakes to avoid

• Rushing the onions: They may lack deep flavour; allow about 25 minutes for caramelising.
• Scorching the onions: Reduce the heat if they brown too quickly, and stir as they cook.
• Boiling throughout: Lower the heat after the broth boils so the soup simmers for 30 minutes.
• Using untoasted bread: Toast the slices first so they are ready to top the soup.
• Grilling unattended: Check the cheese during the 3–5-minute finish to catch it while melted and bubbling.
• Using unsuitable bowls: Choose oven-safe bowls for the grilling step.

How to store

Cool leftover soup and store it covered in the fridge for up to 3 days. Reheat the soup until hot, then add fresh toasted bread and cheese and grill until melted; storing the topping separately helps keep the bread from going soggy.

Frequently asked questions