A Vegetarian French Onion Soup recipe made in the slow cooker with caramelized onions in a rich savory broth. This delicious comforting bowl of soup topped with cheesy croutons(optional) is perfect served for a cozy lunch or dinner. Gluten free with vegan option.
The Fall months are the perfect time to start thinking about all the cozy soup recipes. This vegetarian french onion soup is always one of our go to's!
We love this easy french onion soup recipe in the slow cooker since you only need a few ingredients and minimal prep time.
Some of our other favorite crockpot soup recipes are this cabbage soup or lentil soup.
Jump to:
Ingredients needed
- Onions
- Vegetable broth
- Butter
- Coconut aminos
- Seasonings
- Olive oil
- Balsamic vinegar
- Tapioca flour
Substitutions & notes
- Onions- you can use any large onions you have on hand. I recommend a combination of the yellow with a red onion for an optimal flavor profile.
- Veggie broth- low sodium vegetable broth. Homemade vegetable broth or regular vegetable broth is a good substitute.
- Butter- unsalted butter. To make it vegan just swap with a dairy free butter here.
- Coconut aminos- Braggs aminos or any other gluten free soy sauce is a good substitute..
- Tapioca flour- can swap with non gmo cornstarch. I've tested it with both and either one gives good results.
- Balsamic vinegar- I don't recommend swapping this or leaving it out.
How to make vegetarian french onion soup
full directions are in the recipe card (crockpot, instant pot slow cooker, stovetop methods included) I used the instant pot slow cooker method on this post.
- Add thinly sliced onions to the pot with melted butter and olive oil.
- Cook onions till caramelized and lightly browned.
- Add remaining ingredients and stir.
- Slow cook recommended time per directions in recipe card below.
- Remove bay leaf prior to serving and top with croutons, shredded cheese and broil till melted and lightly browned(optional).
FAQ'S
Typically yellow onions are used but I like to use a variety to give the flavor profile more depth. So I generally will add in a red onion but you can certainly use whatever onions you have on hand.
I used a gluten free dairy free baguette that was toasted and broken into croutons before topping on soup. You could also just do slices but I find it easier to eat with crouton sized bread.
I recommend a good quality cheese that you shred yourself. Some of my favorites are gruyere cheese, swiss cheese, or grand cru cheese.
Yes. Just store the cooled soup in an airtight container in the fridge and top with croutons and cheese right before serving.
Storage notes
This vegetarian french onion soup can be stored without cheesy croutons in an airtight container in the fridge for up to 3 days.
For longer storage it can be frozen in freezer safe containers or bags 3-4 months.
AND IF YOU TRY THIS RECIPE PLEASE BE SURE TO LET ME KNOW IN THE COMMENTS BELOW…..I’d love to hear if you make this & how you like it. Plus please be sure to include a star rating.
Until next time- xoxo
📖 Recipe
Vegetarian French Onion Soup (Slow Cooker)
Ingredients
- 2 large yellow onions thinly sliced
- 1 large red onion thinly sliced
- 4 tbsp. butter unsalted divided
- 1 tbsp. olive oil
- ¼ teaspoon salt
- 1 tbsp. balsamic vinegar
- 2 tbsp. tapioca flour or cornstarch
- ½ tsp. thyme
- 1 bay leaf
- 3 tbsp. Coconut Aminos
- 4 cups Vegetable Broth
- 1 cup water
- cheese of choice
- croutons or crusty bread for topping
Instructions
Instructions for caramelizing onions:
- Melt 2 tbsp. butter with olive oil over medium heat in pan on stove top or instant pot if using.
- Place onions in pan and cook 10 minutes, then sprinkle with salt.
- Cook additional 20 minutes until caramelized and drizzle with balsamic vinegar last couple minutes of cooking.
Crockpot instructions:
- Place caramelized onions in crockpot, along with remaining ingredients reserving cheese and croutons for topping.
- Cook on high 5 hours.
- Remove bay leaf before spoon into bowls.
- Spoon in oven safe serving bowls and top with croutons and cheese.
- Melt until bubbly and golden brown.
Stovetop instructions:
- Follow instructions above for caramelizing onions.
- Add remaining ingredients and cook on low on stovetop 45-55 minutes.
- Remove bay leaf prior to serving and adding cheesy croutons.
Instant Pot instructions using slow cooker function:
- Set the instant pot on the sauté function and melt the 2 tbsp. of butter with olive oil.
- Add thinly sliced onions and stir every few minutes for about 10 minutes before adding salt.
- Continue to sauté onions stirring frequently as needed about 15-20 more minutes till they start to brown and caramelize.
- Drizzle with balsamic vinegar the last minute of cooking.
- Turn off Instant Pot, add remaining ingredients and stir.
- Cover with lid. I recommend using a tempered glass lid that you can get for the instant pot. You can however use the lid that came with the instant pot and set to vent for slow cooking.
- Set Instant Pot to slow cooker function. Adjust to high setting using the + button until you see the more button is on.
- Then set timer for 6 hours and 30 minutes.
- Remove bay leaf, serve immediately or add croutons and cheesy topping and melt under broiler.
Notes
Nutrition
Updated post from October 2016
Dana Stinson-Marone
How many calories?
Stephanie
Approximately 163 calories per serving! This does not include calories for cheese or crouton topping, since that can vary based on your preferences.
Kayla Clark
This recipe is a game changer for me! I love French Onion soup, but it's almost always made with beef broth at restaurants, so I haven't been able to get it since becoming a vegetarian. This soup is so easy, and so good!
Stephanie
Thanks Kayla! Glad you're enjoying it! 😘
Elizabeth
This soup was wonderful! But it's definitely not enough for 6 servings and DEFINITELY not enough for 8. It filled our crockpot about halfway, and we got four bowls out of it. It was scrumptious though.
Aimee Snell
Did you put the bowls in the oven to melt the cheese? If so, what temperature and about how long?
Stephanie
Yes! Just make sure you are using oven safe bowls. Approximately 400 degrees depending on your oven. It should take about 5-8 minutes to get melty but it really depends on how brown you like it. I recommend using a Swiss cheese on this! Hope this helps.
Claudia Stephens
Hi there, would you happen to know the equivalent cook time for cooking in a pot in stovetop as I don’t have a crockpot? Thanks!
Stephanie
Hi Claudia, I haven't actually made this recipe on the stovetop, but I would estimate about 45-60 minutes on low would work. Hope this helps!
Melanie C.
I made this on 12/3/19 with a few minor modifications - doubled the salt and added the same amount of pepper, deglazed the onions with sherry, and added some vegan Worcestershire sauce. It was excellent and such deep flavor! Will be making again soon.
Stephanie
Thanks for stopping by to let me know Melanie! So glad to hear you Enjoyed it! 😘
Kelly
I love this soup thank you so much for the recipe! Just opened this up to make for the 2nd winter in a row. Random question... ingredients list 4 Tbsp of butter but only 2Tbsp for cooking the onions in on the stovetop. When do you use the other 2? I don't think I ever realized I wasn't including them in the crockpot as part of the remaining ingredients or anywhere else when I made this previously! Just wanted to double check! Thanks!
Stephanie
Hi Kelly, I'm sooo glad to hear you're enjoying the soup. The extra 2 tbsp. of butter are to be added to the crockpot with the remaining other ingredients. Sorry that wasn't clear in the recipe card. But it sounds like it's turned out good for you without it. 👍
Kim
Can you freeze this prior to adding the croutons?
Stephanie
I haven't personally tried freezing it. But it should be fine to freeze before adding any cheese or croutons!
Taylor
Hi! Would this be okay to let sit cooking for a few additional hours? Trying to plan dinner for after work. Thanks!!
Stephanie
Hi Taylor, I can't really verify how well it will do if you cook it several more hours on High in the slow cooker since I haven't tried it. You could try cooking it on the Low setting in the slow cooker since that gives you several more hours cooking time. It just depends on how much longer you'll need to let it sit. Hope this helps and let me know how it goes.
Morgan
Can I double the recipe in the crockpot and use the same amount of cook time? I made the original recipe and it was fantastic! Came to about half way up my crockpot but I underestimated the amount of servings. Thanks 🙂
Stephanie
Hi Morgan, Yes you can double the recipe and it should not change how long you cook it in the crockpot. So glad that you Enjoyed it 😀
Danielle
I tried it and it was easy and great! I used dried thyme so I think I would reduce the amount next time but only because that’s my preference. Definitely will make it again!!
Stephanie
Thanks Danielle and glad to hear you enjoyed it 😀
swathi
Looks delicious love this french onion soup.
Amy Katz from Veggies Save The Day
This vegetarian version looks so much better than the traditional one!
Stef
Thanks Amy!
Mindy
Okay, let me just say that your French onion soup looks way better than what I am used to seeing!
Stef
Thanks Mindy! Hope you try it soon 🙂
jacquee | i sugar coat it!
Big fan of French onion soup! Could use a bowl to warm me up today.
Platter Talk
I love french onion soup. Your pictures are making my mouth water.
Stef
Yeah. Then I've done my job. Hope you get to try this 🙂
Marsha | Marsha's Baking Addiction
That cheese! This soup is just mouthwatering!
Beth @ Binky's Culinary Carnival
I'm crazy about French Onion! Love that this is a slow cooker version! I'll give it a try!
Stef
Thanks Beth!
Kristine
I LOVE French onion soup and this recipe looks delicious! Thank you for the recipe, I cannot wait to try it!
Stef
You're welcome Kristine. Hope you enjoy 🙂