I can’t say enough about this recipe! This Vegetarian Onion Soup is just so delicious it is hard to only eat one bowl!
One of the best things about this Vegetarian Onion Soup is that I had the ingredients in the house except for the Gruyere cheese but I have used mozzarella cheese sometimes & it has been good too! I found Gruyere cheese at our Costco so that was great!
The ingredients you need are:
- Onions, I always have onions in the house
- Butter, I have butter in the house but the price is so high now I am sure you can use some oil to sauté the onions
- Green onions, I did have these in the house but only 1 bunch so that is what I used
- Sprigs of thyme: I buy thyme & toss the pkg in the freezer since I do not use often… I wash it then it is ready to use. Use dried thyme if you don not have fresh sprigs
- Bay leaf : Bay leaves last forever so I have these in the house from a long time ago
- Cremini mushrooms: I am sure you can use white mushrooms here or leave them out if you want!
- Sourdough bread: I used some white sourdough bread I had in the house. The bread needs to be hearty but try using salad croutons if you do not have this type of bread!
- Gruyere cheese: I have used mozzarella cheese & it was ok
When Murray & I got married we were given a set of onion soup bowls! I have kept the bowls all of these years, we are married 44 years! I keep them on the very top shelf in one of the kitchen cupboards. I do not use them very much so every time I take them down they need a good wash before using. I suppose I could use them for something else other thank onion soup but I never have!

To prepare this soup ahead of time, make the soup & it can sit on the stove for a bit until you want to put your bowls together. Do not keep the soup out of the fridge for long for food safety reasons. I think you can prepare the soup earlier in the day or even the day before, store in the refrigerator & Just reheat the soup when ready to put into the bowls.
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Here is the recipe from Martha Stewart. I make it exactly as the recipe says to make it ! ( except I used 1 bunch of green onions )
This recipe serves 4 ( we had leftovers )
You will need oven proof bowls for this soup as they will go under the broiler
Ingredients
6 tbsp butter
2 large onions, thinly sliced
1 – 2 green onions (scallions), sliced ( I added the white & green parts of these but after reading the recipe only whites are added & the greens are for garnish!)
4 sprigs of thyme *** 1 sprig of thyme is equal to 1/2 tsp dried thyme so you can use dried if you do not have fresh.
1 bay leaf
12 oz/340 gr mushrooms (cremini), sliced or chopped… your choice!
salt & pepper to taste
4 cups of water
4 slices of sourdough bread – 1 1/4 inch thick
1 1/2 cups (4 oz/113g) Gruyere cheese shredded
Method
- Melt the butter in a medium size saucepan. Add the onions, scallions, thyme sprigs & bay leaf. Stir often so the onions do not stick to the pan or burn. cook until the onions are soft & a lovely golden brown colour. You might lower the heat so the onions do not burn. This will take about 20 minutes depending on hot the heat is
- Add the prepared mushrooms to the onions. Season with salt & pepper. Cook until the mushrooms have released their moisture. Stir often This can take about 15 minutes
- Stir in the water. Bring to a boil, Reduce the heat & simmer for about 5 minutes though I cooked mine longer Remove the thyme sprigs & the bay leaf. Taste & adjust seasonings adding more salt & pepper if needed. At this point you can turn the heat off & keep until ready to serve
- Preheat your broiler before you going to prepare these.
- Put the soup into your oven proof bowls. Add the bread (cut to fit the bowls you are using ) Press the bread down a bit. You can cut the bread into cubes & use it that way in the soup if you do not want a solid piece of bread! Sprinkle some of the grated cheese on top of the bread. Put the bowls under the broiler to melt the cheese. Watch it closely because once the cheese starts to melt it goes fast! I like my cheese edges to be just slightly browned. When the cheese is melted carefully remove from the oven!
Enjoy!
The video I took was very long since it too awhile to cook this soup so I sped it up!
Looks divine! Love an onion soup.