Traditional French Onion Soup, Gratinated – Revisited in the 19th Century

Originally, onion soup was made simply with water, without any broth. The addition of light bone broth is a more recent adaptation to enrich the flavor. The gratin with cheese and croutons became characteristic in the 19th century, especially in Parisian cafés, giving the soup the warm and generous feel we know today.

Traditional Gratinated Onion Soup

Ingredients

• 1 kg yellow onions, finely sliced

• 50 g pork fat (or clarified butter)

• 1.5 liters light bone broth (homemade, simple and clear)

• 1 bouquet garni (thyme, bay leaf, parsley)

• Salt and freshly ground black pepper

• Slices of country-style bread (for croutons)

• 150 to 200 g grated cheese (gruyère, comté, or traditional beaufort)

Preparation

1. Melt the fat in a saucepan.

2. Add the sliced onions and cook gently over low heat until well browned, translucent, and slightly caramelized (30–40 minutes).

3. Add the bouquet garni, salt, and pepper.

4. Pour in the hot light bone broth, bring to a boil, then lower the heat and simmer gently for 45 minutes to 1 hour.

5. Remove the bouquet garni.

6. Preheat the oven to grill mode.

7. Divide the soup into oven-safe bowls.

8. Place one or two toasted slices of bread (croutons) on each bowl and generously top with grated cheese.

9. Grill in the oven until the cheese is melted, golden, and gratinated.

10. Serve immediately.

You can also try one of these well-known variations to your taste.

Famous Variations of Onion Soup

1. Classic Parisian Onion Soup

• Uses rich, dark beef broth for greater depth.

• Often gratinated with grated gruyère and served in handled bowls or cups.

• Croutons are usually thicker and sometimes buttered before grilling.

2. Lyon-style Onion Soup

• Onions are cooked with a large amount of butter, often until deeply caramelized, nearly confit.

• A splash of dry white wine is sometimes added during cooking to enhance flavor.

• The cheese topping may mix gruyère and emmental.

3. Onion Soup with White Wine

• During onion cooking, a little dry white wine (such as Bourgogne aligoté) is added to deglaze the pan.

• Adds slight acidity and extra complexity to the flavor.

4. Gratinated Onion Soup with Comté

• Popular in eastern France (Franche-Comté), this version uses comté instead of gruyère, offering a nuttier, fruitier flavor.

5. Onion Soup without Gratin

• An older or simpler tradition, often served just with onions cooked in water or light broth, without cheese or croutons.

• Closer to rustic, pre-19th-century recipes.

6. Onion Soup with Champagne

Origin: Festive variation, often served as a starter for holiday meals or in fine-dining restaurants.
Features:

• Uses brut Champagne (or crémant) instead of white wine or broth.

• Adds a bright, slightly acidic, elegant note to the soup.

• Can be gratinated like the classic version or served clear to let the Champagne shine.
  Tip: Champagne is added after sautéing the onions to deglaze the pan, and may be topped up with light broth. Use in moderation so it doesn’t overpower the flavor.

7. Onion Soup with Dry White Wine

Origin: Common in Burgundy, Alsace, or Savoie – regions known for quality dry white wines.
Features:

• A dry white wine (such as Bourgogne aligoté, Sylvaner, dry Riesling, or Jacquère) is added during or after the onions are caramelized.

• The wine deglazes the pan, lifts the fond, and enriches the soup’s aroma.

• Can be combined with light bone broth for balance.
  Note: This version remains rustic but gains finesse, preserving the soul of its peasant roots.