Lyonnese-Style Gratinated Onion Soup

🧂 Ingredients

• ✓
  Cebollas amarillas

  1.2 kg
• ✓
  Mantequilla

  50 g
• ✓
  Aceite de oliva virgen extra

  2 cucharadas
• ✓
  Azúcar moreno

  1 cucharadita
• ✓
  Vinagre de Jerez

  1 cucharada
• ✓
  Harina de trigo

  1 cucharada
• ✓
  Vino blanco seco

  150 ml
• ✓
  Caldo de ternera

  1.5 litros
• ✓
  Tomillo fresco

  4 ramitas
• ✓
  Hoja de laurel

  1 unidad
• ✓
  Baguette

  8 rebanadas
• ✓
  Queso Gruyère

  200 g
• ✓
  Sal y pimienta negra

  al gusto

📋 Instructions

1. 1

   Peel and cut the onions into thin julienne strips. In a thick-bottomed pot, melt the butter with the oil over medium-low heat.

2. 2

   Add the onions with a pinch of salt and cook for 45-50 minutes, stirring every 5 minutes, until they are deeply caramelized and dark amber in color. Do not rush this step: patience is the secret.

3. 3

   Increase heat to medium, add the sugar and Sherry vinegar. Cook 2 minutes until the acid evaporates.

4. 4

   Incorporate the flour, stir well and cook 1 minute to eliminate the raw taste.

5. 5

   Pour in the white wine and deglaze scraping the bottom of the pot. Let reduce by half.

6. 6

   Add the hot beef broth, thyme, bay leaf, salt and pepper. Simmer gently for 20 minutes. Adjust salt.

7. 7

   Preheat the broiler to 220°C. Toast the baguette slices in the oven until golden and crispy.

8. 8

   Serve the soup in individual ovenproof bowls. Place one or two toasts on top and cover generously with grated Gruyère.

9. 9

   Gratin under the broiler 3-5 minutes until the cheese bubbles and forms a golden crust. Serve immediately, being careful not to burn yourself.