Ingredients

The following ingredients have 4 Servings
  • 2 tablespoons unsalted butter
  • 1 tablespoon extra virgin olive oil
  • 5 large onions (halved and thinly sliced)
  • 3 cloves garlic (minced)
  • ½ teaspoon salt
  • 2 tablespoons all-purpose flour
  • 8 cups low-sodium vegetable stock
  • 1 teaspoon Dijon mustard
  • 1 teaspoon red wine vinegar
  • ⅔ cup Gruyère cheese (shredded)
  • 4 Slices bread (that fit your dishes the soup will go in.*)

Instruction

  • Heat the butter and oil in a large heavy saucepan over medium heat. Add in the onions, garlic, and salt, and cook 5 minutes, stirring often. 
  • Reduce the heat to as low as possible; cook, stirring occasionally. Cook the onions until they are tender and brown; about 50 to 60 minutes.
  • When the onions are tender, stir in the flour. Cook 3 to 4 minutes, stirring constantly.
  • Stir in the broth, mustard, and red wine vinegar to the onion mixture. Cover, and simmer 15 minutes, stirring occasionally.
  • Preheat broiler.
  • Ladle soup into oven-safe bowls. Top each bowl of soup with a slice of bread and grated cheese. Place the bowls of soup under the broiler.
  • Broil until the cheese is bubbly and golden; about 1 to 2 minutes.
  • Serve hot with extra slices of bread for dipping.