- Prep
- 20 min
- Cook
- 30 min
- Total time
- 50 min
- Yield
- 4 servings
- Difficulty
- EASY
- Calories
- 535 kcal
Quick summary
“Classic French onion soup brings together onions slowly caramelized in butter in a full-bodied dark beef broth. Served with toasted baguette and gratinated Gruyère cheese, it is pure comfort.”
What you need to know
- The patient caramelization of the onion slices in butter develops a dark brown color and deep sweetness.
- The all-purpose flour sprinkled over the onions cooks briefly forming the roux that makes the meat broth velvety.
- Gratinating in the oven at 180°C melts the Gruyère over the bread, creating a golden and bubbling crust.
Ingredients
Main
- 4 large onions cut into thin slices
- 3 tablespoons of butter
- 1 liter beef broth
- 200g of grated Gruyère cheese
- 1 baguette sliced
- Salt and pepper to taste
- 1 tablespoon of wheat flour
Instructions
Principal
- Em uma panela grande, derreta a manteiga em fogo médio. Add the onions and sauté until they are well browned and caramelized.
- Add the wheat flour and mix well, cooking for 1 more minute.
- Gradually, add the beef broth, stirring constantly to avoid lumps.
- Season with salt and pepper to taste. Let the soup cook over low heat for about 20 minutes.
- Meanwhile, preheat the oven to 180°C.
- Place the baguette slices on a baking sheet and take to the oven for 5 minutes to toast lightly.
- After the 20 minutes of cooking, pour the soup into oven-safe bowls.
- Place one or two slices of toasted baguette over each bowl and cover generously with grated Gruyère cheese.
- Place in the oven for 10 minutes or until the cheese is bubbly and golden.
- Remove from the oven and serve hot, decorating with fresh herbs if desired.
Chef's tips
- Do not burn the onion over high heat; keep medium-low heat stirring frequently until it reaches a dark amber tone.
- Toast the baguette slices well before placing them in the bowl so they can support the weight of the cheese without sinking quickly.
- Use oven-safe ceramic ramekins that can withstand the high heat of the oven broiler.
Variations
- With white wine: add half a cup of dry white wine after caramelizing the onion to deglaze the bottom of the pan.
- Touch of fresh thyme: cook a sprig of fresh thyme and a bay leaf tied together in the beef broth.
- Version with cognac: flambe two tablespoons of cognac before adding the flour.
Substitutions
- Traditional Gruyère cheese can be replaced with Swiss Emmental cheese, aged Gouda cheese, or Steppe cheese.
- Beef broth can be replaced with rich vegetable broth or reduced homemade chicken broth.
- French baguette can be swapped for slices of rustic Italian bread or sourdough bread.
How to store
Store the liquid base of the soup with the onions in a closed container in the refrigerator for up to 3 days without the bread and cheese. At the time of serving, heat the broth in the pot, place in the bowl with the bread, and gratinate in the oven.
Can it be frozen?
You can freeze only the cooked onion broth in airtight containers for up to 3 months. Thaw in the refrigerator for 12 hours, heat until boiling, and assemble the bowls with the baguette and cheese to gratinate at the moment.
What to serve with
Serve steaming straight from the oven-safe bowls as a cozy main dish on cold winter nights. Pairs perfectly with a glass of light French red wine like Côtes du Rhône or Beaujolais.
Frequently asked questions
Does the baguette bread not get too soft and fall apart in the hot soup?
Toasting the baguette slice beforehand in the oven dehydrates the dough, creating a crispy base that supports the melted cheese.
What is the purpose of adding the tablespoon of wheat flour to the onion?
The flour creates a light roux with the hot butter, preventing the beef broth from becoming watery and thin in the bowl.
Why does the caramelization of onions take time and cannot be rushed?
High heat burns the ends of the onions, making the dish bitter; low heat transforms starches into sugars in a sweet and uniform way.
Can I gratin in the microwave instead of the conventional oven?
The microwave only melts the cheese without browning or creating the characteristic crispy gratin crust that the electric oven produces.
