Prep Time::20 mins
Cook Time:: 2 hrs
Total Time:: 2 hrs 20 mins
Servings::4
Ingredients
2 tablespoons salted butter
2 tablespoons olive oil
2 large red onions, thinly sliced
2 large sweet onions, thinly sliced
2 teaspoons kosher salt
1 teaspoon white sugar
4 cups mushroom broth (such as Pacific Foods)
⅔ cup fino dry sherry
1 tablespoon vegan Worcestershire sauce (such as The Wizard's)
2 teaspoons dried parsley
2 teaspoons herbes de Provence
2 bay leaves
1 tablespoon balsamic vinegar
1 (1 ounce) piece Parmesan cheese rind
salt and ground black pepper to taste
8 French baguette slices
¾ cup grated Gruyère cheese
½ cup grated Parmesan cheese
Directions
Melt butter with olive oil in a large 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.
Pour mushroom broth, sherry, Worcestershire sauce, parsley, herbes de Provence, and bay leaves into caramelized onion mixture. Bring to a simmer and cook over medium-low heat for 45 to 60 minutes.
Reduce heat to low and remove bay leaves. Pour balsamic vinegar into soup and adjust seasoning. Mix well.
Place Parmesan cheese rind in the center of the pot and submerge, but do not stir. Cook soup for 20 more minutes.
Meanwhile, set an oven rack about 6 inches from the heat source and preheat the oven's broiler.
Arrange baguette slices on a baking sheet.
Toast baguette slices under the preheated broiler for 2 to 3 minutes per side. Remove from the oven and set aside.
Carefully remove cheese rind from the pot and discard.
Fill 4 oven-safe bowls evenly with soup and sprinkle each lightly with Gruyère and Parmesan. Top each with 2 baguette slices and sprinkle with remaining Gruyère and Parmesan. Place the soup bowls on a baking sheet.
Broil soup in the preheated oven until cheese is browned and bubbling, 3 to 5 minutes.
Recipe Tips
Slice onions as thin as possible for the best presentation and texture. If desired, you can use yellow onions instead of sweet onions.
You can substitute dry white wine for fino dry sherry and dried thyme for herbes de Provence.
You can add another 32-ounce carton mushroom broth if you prefer a thinner, soupier consistency; the recipe, as written, produces a thick soup.