Most French onion soup recipes call for beef stock, but substituting mushroom broth instead creates a surprisingly rich soup, full on flavor - without the meat. Could become a staple recipe in vegetarian or meat-loving households! A long cooking time and savory ingredients mean this soup is pretty darn rich. Add in the toasted baguette slices and all that gooey Gruyere... this soup is definitely the main course. Serve alongside a crisp, green salad.
Preparation Time
20 mins
Cooking Time
2 hr
Total Time
2 hr 20 mins
Calories
478 Calories
Recipe Instructions
Step 1
Set an oven rack about 6 inches from the heat source and preheat the oven's broiler.
Step 2
Melt butter and olive oil in a pot over medium heat. Add red onions and sweet onions; sprinkle with kosher salt and sugar. Cook, stirring frequently, until onions are very tender and caramelized, about 45 minutes.
Step 3
Pour mushroom broth, sherry, Worcestershire sauce, parsley, herbes de Provence, and bay leaves into onion mixture. Bring to a simmer and cook over medium-low heat for 45 to 60 minutes.
Step 4
Reduce heat to low and remove bay leaves. Pour balsamic vinegar into soup and adjust seasoning. Mix well.
Step 5
Place Parmesan cheese rind in the center of the pot and submerge, but do not stir. Cook soup for an additional 20 minutes.
Step 6
Arrange bread slices on a baking sheet.
Step 7
Broil bread slices in the preheated oven for 2 to 3 minutes per side. Remove from the oven and set aside.
Step 8
Carefully remove cheese rind from the pot and discard.
Step 9
Fill 4 oven-safe bowls evenly with soup and sprinkle each with a light layer of grated Gruyere cheese and Parmesan cheese. Top each with 2 bread slices and sprinkle each with remaining Gruyere cheese and Parmesan cheese. Place bowls on a baking sheet.
Step 10
Broil soup in the preheated oven until cheese is browned and bubbling, 3 to 5 minutes.
Ingredients
1 teaspoon white sugar
2 tablespoons olive oil
½ cup grated Parmesan cheese
2 teaspoons dried parsley
2 teaspoons kosher salt
salt and ground black pepper to taste
2 bay leaves
1 tablespoon balsamic vinegar
2 large sweet onions, thinly sliced
2 tablespoons salted butter
2 large red onions, thinly sliced
2 teaspoons herbes de Provence
¾ cup grated Gruyere cheese
4 cups mushroom broth (such as Pacific Foods™)
⅔ cup fino dry sherry
1 tablespoon vegan Worcestershire sauce (such as The Wizard's)