Onion Gratin (Gratinated Onion Soup)

Ingredients

• 4 pcs Yellow onions (Peeled and thinly sliced into fine strips)
• 30 g Butter (Divided in two, one part for the onions, one for the croutons)
• 2 c. à soupe Olive oil (For cooking the onions and brushing the bread)
• 1 c. à café Salt (Seasoning)
• ½ c. à café Ground black pepper (Seasoning)
• 100 ml Dry white wine (Deglaze the onions, adds a slight acidity)
• 500 ml Vegetable broth (Can be homemade or from a cube)
• 4 tranches Country bread or baguette (Sliced about 1 cm thick)
• 1 pcs Garlic clove (Optional, rubbed on the bread slices before cooking)
• 150 g Grated Emmental cheese (Can be replaced with Comté or Gruyère)

Instructions

1. Prepare the onions

   Peel the onions then thinly slice them into regular strips.

   Time: PT5M

2. Caramelize the onions

   Melt 15 g butter with 1 c. à soupe olive oil in the sauté pan over medium heat. Add the onions, season with salt and pepper, and stir. Gradually increase the heat and cook while stirring often until they reach a deep golden-brown color (15 min).

   Time: PT15M

3. Deglaze with white wine

   Pour the white wine into the pan, scraping the browned bits from the bottom. Let it reduce by half (2 min).

   Time: PT2M

4. Simmer the soup

   Add the vegetable broth, cover and let simmer over low heat for 20‑30 min (we take 25 min). Stir occasionally.

   Time: PT25M

5. Prepare the croutons

   Preheat the oven to 200 °C (no fan). Brush the bread slices with olive oil, lightly rub with the garlic clove (optional) and place them on the tray. Bake for 10 min until golden and crisp.

   Time: PT15M

   Temperature: 200°C

6. Assemble the soup

   Pour the hot soup into ramekins, place one or two crouton slices on each bowl and generously sprinkle with grated cheese.

   Time: PT5M

7. Gratin in the oven

   Place the ramekins under the oven's grill (grill setting) for 4‑5 min, until the cheese is melted and nicely browned.

   Time: PT5M

8. Rest and serve

   Let rest for 2 min before serving so the cheese sets.

   Time: PT2M

Nutrition Facts

Calories

350

Protein

15 g

Carbohydrates

30 g

Fat

15 g

Fiber

4 g

Ingredient Substitutions

• Instead of Butter: olive oil
• Instead of Olive oil: sunflower oil
• Instead of Dry white wine: sweet cider
• Instead of Vegetable broth: water + bouillon cube
• Instead of Country bread or baguette: whole grain bread
• Instead of Grated Emmental cheese: Comté, Gruyère

Equipment Needed

• Sauté pan or large skillet
• Chef's knife
• Cutting board
• Baking sheet
• Oven
• Ladle
• Ramekins or gratin bowls
• Wooden spatula
• Kitchen tongs (optional)

Critical Steps — Do Not Skip

• Caramelize the onions without burning them
• Properly deglaze with white wine to lift the browned bits
• Gratin the cheese under the grill without burning it

Chef Tips from the Video

• Add a pinch of sugar during caramelization to speed up browning.
• A splash of cognac or brandy before gratinating adds extra aromatic depth.
• Use slightly stale country bread for crispier croutons.

Troubleshooting

Storage

Refrigerator: Store leftovers in an airtight container for 3 to 4 days.

Freezer: Not recommended; the texture of the bread and cheese degrades.

Room temperature: Croutons can be kept for 2 days in a bread box.

Make-Ahead Tips

• Caramelize the onions the day before and store them in the refrigerator; gently reheat before adding the broth.
• Prepare the croutons ahead of time and store them in an airtight container.