Cozy up with a rich, decadent bowl of Vegetarian French Onion Soup. It's just as savory and satisfying as the classic version - you won't miss the beef broth with this umami-loaded, super flavorful broth and everyone's favorite cheesy bread topping.
Caramelize Onions: Melt butter in a large stainless steel stock pot over medium-high heat. Add sliced onions and stir to coat with a pinch of salt. Cook, stirring occasionally until softened, for 5-8 minutes. Reduce heat to medium-low and continue to cook onions, stirring occasionally, until they are a deep golden brown and sweet. If the bottom of the pan gets close to burning and becomes too dry, deglaze the pan with 1-2 tablespoons of water, scraping up the brown bits, and continue to cook. The caramelization process will take around 45 minutes to an hour, depending on how thinly you sliced the onions and your temperature. It’s a low and slow process for the best flavor - don’t rush this part.
Once caramelized, add the garlic, thyme, and bay leaf. Stir to combine. Increase the heat to medium and deglaze the pan with red wine, scraping up any brown bits on the bottom as you do so. Let it simmer for 1-2 minutes.
Add the vegetable stock and bring to a simmer for about 20 minutes. Add salt and pepper to taste. Be sure to taste test and adjust salt levels as needed; the flavor will develop the longer the soup sits and simmers.
Add Worcestershire sauce and apple cider vinegar. Feel free to add a little and increase to taste, if preferred. Remember to check for salt and pepper levels, too!
Crostini: Preheat oven to 425°F. Brush both sides of the bread slices with olive oil and place on a baking sheet. Bake in the oven for 5-7 minutes, flipping halfway through as needed, until toasted and golden brown. Toss diced bread with olive oil and place on the baking sheet, too, if using.
Option 1 for Topping: Preheat broiler to 475°F. Spoon a little soup into the bottom of individual, oven-safe bowls. Add a toasted bread slice (or croutons). Top the bread with another scoop of soup, then add 1-2 additional bread slices and sprinkle the top of the cheese with gruyere (and sprinkled parmesan as desired). Place under the broiler for 3-4 minutes until cheese is melted and golden brown.
Option 2 for Topping: After toasting the bread, sprinkle cheese on top of the slices on the baking sheet and place back in the oven, turn on the broiler, and broil until the cheese is melted, about 3-4 minutes. Then, top individual serving bowls with the cheesy bread.
Garnish with additional grated parmesan cheese, thyme, or fresh chives as desired. Enjoy!
Notes
This recipe yields approximately 8 cups of soup.
Be sure to use an oven-safe bowl or ramekins, if broiling the individual soup bowls.
Look specifically for vegetarian cheese, or substitute with a preferred type.
Gluten-Free: use gluten-free bread.
Make-Ahead: prepare the soup through step 4 and store in an airtight container in the fridge. When ready to serve, continue preparing and topping with the bread.
Storage: place the soup in individual containers in the fridge for up to 5 days. When ready to serve again, top each dish with bread/cheese as desired.
To freeze: similarly, freeze the soup on its own. I recommend using SouperCubes for easy individual-sized portions that are perfect for grab-and-go or quick dinners.