Vegetarian French Onion Soup

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.

There’s just something about silky caramelized onions topped golden, crusty cheese that takes your breath away every time. This is classic French cooking at its finest. It’s not just the flavor. It’s the promise that while the outside world is cold and brutal, every spoonful of French onion soup is pure bliss. This vegetarian French onion soup is our spin on the classic: it’s so full of rich, nuanced flavor you won’t miss the traditional beef broth. It’s a bit of a project: but it’s worth every moment of the prep. Promise!

How to make French onion soup: an overview

French onion soup has a long history; onion soups go back as far as the Roman times. But the modern version of French onion soup comes from Paris in the 1700’s. It was introduced in the US in the 1860’s in a New York restaurant, and it’s been popular ever since.

You’ll need about 1 1/2 hours to make this vegetarian French onion soup. But it is 100% worth the effort, and you can make a few components in advance as time savers. Make it on a cozy day when you have time to prep, or do the advanced prep if you’re serving for a dinner party.

Caramelize the onions	1 hour
Make the vegetarian broth	30 minutes (while cooking onions)
Make the soup	20 minutes

The key to vegetarian French onion soup: homemade broth

Here’s one important thing to note. Vegetable broths and stocks vary widely in flavor and quality. Try it in a French onion soup, and most purchased veggie broth comes out sweet: not savory like you’d expect! Trust us, we tested a few times and it did not taste right.

Here’s what you’ll have to do: make a homemade vegetable broth! It might sound like overkill, but it makes for just the right flavor. When Alex and I tried it with this homemade broth, we were amazed by the flavor. Don’t skip this step!

Of course, if you want a classic French onion soup: just use beef broth! You can make the same recipe without that step and of course, it tastes great too.

Caramelizing onions: a few tips

The main time-consuming step for vegetarian French onion soup is caramelizing the onions! Sure, you can saute onions in about 10 minutes. But to get them fully dark brown and caramelized takes about 1 hour. Here are the basic steps, and a graphic that shows the color of the onions each phase!

Thinly slice the onions.
Sauté the onions in butter for 10 minutes on medium high.
Reduce the heat to medium low, add salt and saute for 40 to 45 minutes until deep brown and very soft.

Dry sherry brings big flavor (or use white wine)

This vegetarian French onion soup uses dry sherry to bring in complexity and intrigue into the flavor. What is it, and what’s a substitute?

Sherry is a fortified wine made in Spain that’s made by adding grape liquor to white wine. The flavor is sharp, with a scent of apple cider and a very dry finish. It’s worth finding for this recipe if you don’t have it already.
How long does sherry last? An opened bottle of sherry lasts in the refrigerator for 2 to 3 months.
What’s a substitute for sherry? Don’t’ have it? You can use a dry white wine instead (make sure it’s not a sweet wine).

The crouton topping: broil or bake!

The last component to a great vegetarian French onion soup is the crouton topping! That is: it’s topped bread and cheese, broiled to golden perfection. There are a few techniques to achieve this, but I love the one that Alex devised using both Swiss cheese and grated Parmesan. Here’s what to do:

Place the soup into small oven-safe bowls or ramekins. This is key! Make sure you have some small serving bowls: typically this soup is not served in large vessels.
Add 1/2 inch slices of bread, then Swiss or Gruyere and grated Parmesan cheese. The two cheese really makes the perfect melting. Remember: grated Parm is the kind that looks like snow (don’t use shredded).
Broil for 2 minutes or bake 20 minutes at 400 degrees. The broiling method here is much easier and quicker: we prefer it! But if you don’t have a broiler, go the oven route.

Make ahead tips for vegetarian French onion soup

Last tip before we get to this (very tasty) recipe: here’s how to speed it up! You can make both of the main components in advance:

Caramelize the onions in advance. This makes the prep time take next to nothing! Caramelize the onions, then refrigerate until serving. Bring to warm before you pick up in the soup recipe.
Make the homemade broth in advance. Same idea! You can refrigerate until serving, then warm it up and pick right back up in the recipe.

What to serve with French onion soup

Here’s a final important thing to note about French onion soup: it’s not intended as a full meal. It’s generally served as an appetizer to an elegant meal, or as a lunch. How to make it into a light meal? Here’s what to add:

Salads like Arugula Salad, Arugula Beet Salad, Pomegranate Salad, Brussels Sprouts Salad, or Fennel Orange Salad
Sandwiches like Pear & Cheese Sandwich
Seafood (if you eat pescatarian!) like Quick Broiled Salmon, Seared Scallops, or Pan Fried Cod

This vegetarian French onion soup is…

Vegetarian. For gluten-free, use gluten-free bread.