Soupe à l’Oignon Gratinée

Name: Soupe à l’Oignon Gratinée
Prep time: 10 min
Cook time: 35 min
Yield: 3 to 4 servings
Cuisine: French Menu
Ingredients: Yellow Onions — 4 large; Butter — 50 g; Beef Stock — 1 litre; Nutmeg — 1 pinch; Baguette — 1; Hard Cheese — 150 g; Salt — To taste; Black Pepper — To taste

This classic French onion soup, or soupe à l'oignon, is a rustic masterpiece featuring sweet, slow-cooked golden onions simmered in a rich beef broth and topped with a toasted baguette slice and bubbling, melted cheese. This deeply comforting dish relies on time and patience to develop a sweet, caramelised flavour profile, creating an elegant, soul-warming bowl that remains a quintessential highlight of traditional French brasserie cuisine.

Cuisines

Cooking Instructions

Preparation: 10 minutes
Cooking: 35 minutes

Servings: 3 to 4

Notes:

Use the largest yellow onions available to minimise preparation time; slice them into thin, consistent strips no thicker than 3 mm to ensure they caramelise evenly and develop a sweet, compote-like texture without burning.

Patience is the secret ingredient; sauté the onions in butter on low heat for 15 to 20 minutes until they achieve a deep, beautiful blonde colour, which creates the foundation of the soup's flavour, and add a pinch of sugar if the onions are too sharp or pungent.

For the bread, day-old baguette is ideal; slice into 1 cm thick rounds and toast them in the oven at 180°C until dry and slightly coloured, which prevents them from becoming overly soggy when submerged in the hot soup.

Beef stock is the traditional choice for a robust, classic profile, but a high-quality poultry or vegetable stock works beautifully for a lighter version, provided it has a good, rich colour.

If the final soup consistency appears too thin, a small amount of cornflour mixed with cold water and stirred into the simmering broth can quickly achieve that signature, velvety, unctuous mouthfeel.

Prepare Onions
Slice the onions into thin strips no thicker than 3 mm and sauté them gently in a large knob of butter over medium heat, seasoning with salt, pepper, and nutmeg.

Caramelise
Cook the onions slowly for 15 to 20 minutes, stirring occasionally, until they reach a deep, golden blonde colour.

Simmer Soup
Pour in the beef stock, bring the mixture to a gentle simmer, and cook for 10 minutes to allow the flavours to meld completely.

Prepare Gratin
Slice the baguette into 1 cm rounds and toast them in a 180°C oven until dry, then ladle the soup into oven-safe bowls, place a toasted bread slice in the centre, and top generously with grated cheese.

Gratinate
Place the bowls in the oven at 180°C (or under the grill) for a few minutes until the cheese is melted and beautifully golden, then serve immediately.