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vegetarian french onion soup with caramelized onions and melted gruyere cheese in an orange cast iron pot, close-up

Vegetarian French Onion Soup

This vegetarian French onion soup combines caramelized yellow onions, vegetable stock, and apple cider vinegar without wine. Each bowl is finished with garlic-rubbed baguette and melted cheese.
Recipe Developer-Estefania
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Prep Time 10 minutes
Cook Time 1 hour 10 minutes
Total Time 1 hour 20 minutes

Ingredients

For the soup

  • 1 kg yellow onions weighed after peeling and thinly sliced
  • 2 tablespoons unsalted butter
  • 1 teaspoon vegetable oil
  • 1 teaspoon salt
  • 1 tablespoon all-purpose flour
  • 1 tablespoon apple cider vinegar
  • 1 l low-sodium vegetable stock
  • 2 bay leaves

For the topping

  • 4 baguette slices one per bowl
  • 1 garlic clove for rubbing the toast
  • 100 g Gruyère cheese grated; choose cheese labeled suitable for vegetarians

Instructions

  • Melt 2 tablespoons unsalted butter with 1 teaspoon vegetable oil in a large, heavy pot over medium heat. Add 1 kg yellow onions , thinly sliced, and 1 teaspoon salt. Reduce the heat to medium-low and cook for 30–40 minutes, stirring occasionally, until the onions are soft and deeply golden. 
  • Sprinkle 1 tablespoon all-purpose flour over the onions. Stir to coat and cook for 2–3 minutes. Add 1 tablespoon apple cider vinegar, scrape up the browned bits from the bottom of the pot, and cook for another 2–3 minutes. 
  • Gradually pour in 1 l low-sodium vegetable stock while stirring to incorporate the flour smoothly. Add 2 bay leaves, bring to a gentle simmer, and cook for 15–20 minutes. 
  • While the soup simmers, toast 4 baguette slices until crisp and golden. Rub the toasted surfaces with 1 garlic clove. 
  • Remove the bay leaves and divide the hot soup among 4 broiler-safe bowls. Place 1 baguette slice on each bowl of soup, then divide 100 g Gruyère cheese evenly over the bread. 
  • Broil for 2–3 minutes, until the cheese melts, watching closely to prevent burning. Carefully remove the bowls, let stand for 1 minute, and serve the French onion soup hot.

Notes

Vegetarian cheese: Check the cheese label or manufacturer information for vegetarian suitability. Some Gruyère contains animal rennet, so vegetable stock alone does not make the finished soup vegetarian. 
Peeled onion weight: Measure the onions after peeling to obtain the full quantity needed for the soup base. 
Bread fit: Choose baguette slices that fit inside the bowls so the bread can support the cheese without overhanging the rim. 
Broiler-safe bowls: Use dishes specifically rated for the broiler. An oven-safe label alone does not establish suitability for direct broiler heat. 

Nutrition

Calories: 932kcal | Carbohydrates: 149g | Protein: 34g | Fat: 22g | Saturated Fat: 10g | Polyunsaturated Fat: 5g | Monounsaturated Fat: 5g | Trans Fat: 0.2g | Cholesterol: 43mg | Sodium: 3309mg | Potassium: 705mg | Fiber: 10g | Sugar: 25g | Vitamin A: 949IU | Vitamin C: 19mg | Calcium: 577mg | Iron: 9mg
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