Caramelized Balsamic-Red Onion Soup with Cheese-Topped Croutons Recipe

Ingredients (11)

• 1/4 cup olive oil
• 1 tablespoon butter
• 6 large red onions, thinly sliced
• 2 teaspoons salt
• 1/4 cup balsamic vinegar
• 2 tablespoons soy sauce
• 2 tablespoons prepared mustard
• 6 cups water
• 1/8 teaspoon freshly ground black pepper
• 6 slices French bread
• 3/4 cup grated Swiss cheese