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Vegetarian French Onion Soup

Vegetarian French Onion Soup

  • Author: Sonja Overhiser
  • Prep Time: 5 minutes
  • Cook Time: 1 hour 15 minutes
  • Total Time: 1 hour 20 minutes
  • Yield: 6 1x


This vegetarian French onion soup is the ultimate comfort food! It’s got the rich flavor of the classic, topped with a golden crust of cheese.



For the caramelized onions

  • 2 tablespoons butter
  • 3 pounds yellow onions (5 medium)
  • 1 teaspoon kosher salt
  • 1/2 cup dry sherry (or white wine)
  • 1 tablespoon flour

For the soup

  • 2 tablespoons butter
  • 8 ounces mushrooms
  • 1 carrot
  • 2 celery ribs
  • 6 garlic cloves
  • 9 cups water, divided
  • 2 tablespoons tomato paste
  • 1 teaspoon each garlic powder and onion powder
  • 1 teaspoon vegan Worcestershire sauce (purchased or use this substitute)
  • 2 teaspoons kosher salt
  • 6 slices Swiss or Gruyere cheese (or shredded)
  • 6 tablespoons grated Parmesan cheese
  • 6 large or 12 small slices bread, sliced about 1/2” thick


  1. Caramelize the onions: Thinly slice the onions about 1/8-inch thick (we used a French cut by slicing stem to root; go to minute 1:40 of the linked video for a tutorial). In a soup pot, heat the butter over medium high heat. Add the onions and sauté for 8 to 10 minutes, stirring often, until very soft and just starting to brown on the bottom. Reduce to medium-low heat and stir in the kosher salt. Cook for 40 to 45 minutes, stirring every 5 to 10 minutes and adjusting the heat so they continue to cook slowly without burning. The onions will change from raw to golden to light brown to very dark brown, and reduce in volume by about 1/4. (Make ahead tip: Make the caramelized onions in advance and refrigerate until ready to make the soup. Reheat in a pan and go to step 3.)
  2. Meanwhile, make the homemade broth: Slice the mushrooms. Wash and cut the carrot in half length-wise, then into large chunks. Cut the celery into large pieces. Smash and peel the garlic. In a second pot, heat the butter over medium heat. Add the mushrooms and sauté until browned, about 6 to 7 minutes. Add 8 cups water, kosher salt, mushrooms, carrot, celery, garlic, tomato paste, garlic powder, onion powder, and Worcestershire sauce. Bring to a boil and simmer for 30 minutes. (Make ahead: Make the broth in advance and refrigerate until serving. Then warm before proceeding to Step 3.)
  3. Simmer the soup: When onions are very reduced and dark brown, stir in the sherry and deglaze the pan by scrape all the bits off the bottom of the pan. Sprinkle with the flour and stir until the onions are coated. Strain the homemade broth into the onions (discarding the vegetables). Add the remaining 1 cup water and bring to a simmer for 2 minutes.
  4. Broil the topping: Place the soup into 6 oven-safe small bowls or ramekins. Preheat a broiler to high or an oven to 400 degrees Fahrenheit. Top with bread slices (about 1/2-inch thick), 1 slice Swiss or Gruyere cheese, and 1 tablespoon grated Parmesan per bowl. Broil 1 to 3 minutes (or bake for 20 minutes) until the cheese is melted and browned. Place on a plate and serve immediately, taking care since the bowls are very hot. 
  • Category: Main Dish
  • Method: Stovetop
  • Cuisine: French
  • Diet: Vegetarian

Keywords: Vegetarian French onion soup, French onion soup, How to make French onion soup