Equipment
Ingredients
Soup Base
- 1000 g yellow onions, peeled and thinly sliced
- 60 g unsalted butter
- 3 garlic, minced
- 250 ml dry hard apple cider
- 1000 ml beef broth
- 5 g fresh thyme, tied in a bundle
- 2 bay leaf, whole
- 10 g salt
- 2 g black pepper, freshly ground
Topping
- 200 g baguette, sliced 2cm thick
- 150 g gruyere cheese, freshly grated
Nutrition (per serving)
Nutrition is estimated per serving. Nutrients without complete source data are omitted.
Full nutrition
- Calories
- 560 kcal
- Protein
- 23 g
- Carbohydrates
- 55 g
- Fat
- 26 g
- Fiber
- 6 g
- Sugar
- 17 g
- Sodium
- 2484 mg
- Saturated Fat
- 15 g
- Trans Fat
- 0 g
- Monounsaturated Fat
- 8 g
- Polyunsaturated Fat
- 2 g
- Cholesterol
- 74 mg
- Potassium
- 657 mg
- Calcium
- 500 mg
- Iron
- 3.5 mg
- Magnesium
- 64 mg
- Phosphorus
- 400 mg
- Zinc
- 2.5 mg
- Vitamin A
- 209 mcg
- Vitamin C
- 23 mg
- Vitamin D
- 0.2 mcg
- Vitamin E
- 0.6 mg
- Vitamin K
- 4 mcg
- Vitamin B6
- 0.5 mg
- Vitamin B12
- 0.8 mcg
- Thiamin
- 0.51 mg
- Riboflavin
- 0.46 mg
- Niacin
- 4.8 mg
- Folate
- 119 mcg
- Water
- 557 g
Sources: Aggregated Public Data, USDA FoodData Central
Method
Melt the unsalted butter in a heavy-bottomed Dutch oven over medium-low heat. Add the sliced yellow onions and half of the salt. Cook slowly, stirring every 5 minutes, until the onions reduce and turn a deep, rich mahogany brown. This caramelization process requires patience and takes about 45 minutes.
Pour the dry apple cider into the Dutch oven to deglaze the pot. Use a wooden spoon to firmly scrape the bottom and sides of the pot, dissolving all the caramelized fond into the liquid. Increase the heat to medium and cook until the cider has almost entirely evaporated, about 5 minutes.
Add the minced garlic and cook for 1 minute until fragrant. Pour in the beef broth, then add the bundled fresh thyme, bay leaves, remaining salt, and black pepper. Bring the soup to a gentle boil, then reduce the heat to low, cover partially, and simmer for 30 minutes to meld the flavors.
While the soup simmers, preheat your oven to 200°C/400°F. Arrange the baguette slices in a single layer on a baking sheet. Toast in the oven for 10 minutes, flipping halfway through, until completely dry and lightly golden. Remove from the oven and set aside.
Remove and discard the thyme bundle and bay leaves from the finished soup. Place four oven-safe crocks on a sturdy baking sheet. Ladle the hot soup evenly into the crocks, leaving about 2cm of space at the top. Float 1 to 2 toasted baguette slices on the surface of each bowl, then mound the freshly grated Gruyere cheese generously over the bread, ensuring it touches the edges of the crocks.
Preheat the oven broiler to 260°C/500°F. Transfer the baking sheet with the filled crocks into the oven. Broil for 3 to 5 minutes, watching very closely, until the cheese is heavily bubbling, completely melted, and features distinct golden-brown spots. Carefully remove from the oven and let rest for 5 minutes before serving.
Chef's Notes
- Patience is the single most important ingredient in this recipe. Do not attempt to rush the caramelization process with high heat; true depth of flavor requires 40 to 45 minutes of slow cooking.
- Substituting dry hard cider for the traditional white wine or sherry provides a brilliant autumnal sweetness and acidity that beautifully balances the rich, beefy broth.
- For the ultimate cheese crown, let the grated Gruyere cascade slightly over the rims of the crocks before broiling. The cheese that crisps against the outside of the hot ceramic is often considered the best bite.
- If your crocks are very wide, consider rubbing a raw garlic clove over the toasted bread slices before placing them in the soup to elevate the aromatic profile.
Storage
Refrigerator: 4 days — Store soup separately from the bread and cheese topping.
Freezer: 3 months — Freeze the soup base only. Do not freeze the assembled crocks.
Reheating: Reheat soup on the stovetop until simmering, then assemble with fresh toasted bread and cheese and broil.
Troubleshooting
Onions are crisping or burning instead of caramelizing
Cause: Heat is too high or onions are not being stirred frequently enough
Fix: Immediately remove from heat, add 2 to 3 tablespoons of cold water to stop the cooking and lift the burnt spots, then lower the heat before resuming
Prevention: Maintain medium-low heat and monitor the onions, stirring systematically
Bread completely dissolves into mush instantly
Cause: Baguette slices were fresh and not toasted long enough to dehydrate
Fix: Cannot be fixed once submerged
Prevention: Ensure bread is baked until entirely dry and crisp, like a crouton
Cheese forms a stubborn, greasy clump rather than melting smoothly
Cause: Used pre-shredded bagged cheese coated in anti-caking agents
Fix: Cannot be fixed
Prevention: Always grate cheese fresh from a block for melting applications
Cultural Context
Onion soup has ancient origins stretching back to Roman times, traditionally viewed as peasant food due to the cheap abundance of onions. The iconic modern gratinated version, featuring robust meat broth, toasted bread, and melted cheese, rose to prominence in 19th-century Paris. It was famously served at the bustling Les Halles market, providing a restorative, hearty meal for both early morning laborers and late-night socialites.
