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.
- Vegetable broth
- Coconut aminos
- 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).
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.
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
Vegetarian French Onion Soup (Slow Cooker)
- 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 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.
- 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.
- 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.
Updated post from October 2016