Easy onion soup is wonderfully rich and flavorful. The perfect choice for cold winter days, it's warm, tasty, and comforting.
I suppose you won't be shocked to learn that soup is my favorite lunch to have during the winter. It's one of life's little pleasures - eating a bowl of steaming hot soup (or drinking hot chocolate!) on a truly cold day, one of those days where no matter how many layers you wear, you can't seem to get warm.
This soup is especially good. It's rich, flavorful, and comforting. The secret is to cook the onions slowly and patiently until they are well-caramelized. That's where this soup gets its wonderful flavor.
No cheese in this soup
I do enjoy the classic recipe, but I actually dislike the thick slab of melted cheese that often lays on top of it. So I make mine without it.
When my husband and I were dating, years ago, he had this old, worn-out cookbook. In that first winter together, he made me onion soup out of that cookbook. It was the simplest recipe - he used a bouillon cube to make the broth! But I remember it as one of the best soups I have ever tasted. 🙂
My husband used to serve his soup with grated gruyere cheese on the side so that if you did like cheese in your soup, you could simply stir it in. So that's an option too.
The ingredients needed for this recipe
You'll only need a few simple ingredients to make this rich onion soup. The exact measurements are included in the recipe card below. Here's an overview of what you'll need:
Unsalted butter: I love using creamy European butter, but any butter will be great.
Fresh onions: I don't recommend using frozen onions in this recipe. Fresh is definitely the way to go.
All-purpose flour: I use a little of it to thicken the soup. So this is obviously NOT a gluten-free recipe.
Dry white wine: I like to use sauvignon blanc. This is not a mandatory ingredient - you can omit it. But it does enhance the soup's flavor.
Beef broth: Homemade is great, but store-bought is fine too. It's also fine to use chicken broth. The soup will still taste great, but its color will appear lighter.
Seasonings: I use just a pinch of salt, freshly ground black pepper, and dried thyme. If you use low-sodium broth, you might want to add a bit more salt, so taste and decide.
How to make onion soup
It's so easy! Scroll down to the recipe card for the detailed instructions. Here are the basic steps:
1. Start by patiently cooking the onions in butter until caramelized. This should take about 20 minutes.
2. Mix in the flour and brown it.
3. Next, add the wine and cook to reduce it.
4. Add the beef broth and the spices and simmer until the soup is thickened, about 20 minutes.
How to serve this soup
It's excellent just as it is! As I said above, you can serve it with grated gruyere cheese on the side, allowing each diner to decide if they want cheese in their soup.
For those who do eat cheese, this soup is also good with almond flour cheese muffins or with almond flour cheese biscuits.
Not a gluten-free recipe
I should note that this is not a gluten-free recipe, nor is it low-carb. I use a small amount of white flour in this onion soup to thicken it.
If you must avoid gluten, you might find success with gluten-free flour. Other options include using a cornstarch slurry at the end of cooking (try one tablespoon cornstarch mixed with 1 ½ tablespoon of cold water) or simply omitting the thickener. I haven't tried any of these options, though.
What about leftovers?
Leftovers of this soup keep well in the fridge, in a sealed container, for 3-4 days. I reheat them in the microwave, covered, on 50% power.
More tasty soup recipes
If you enjoy soups, you should definitely check out my collection of soup recipes! One of my favorites is this flavorful egg drop soup. And this cream of broccoli soup is wonderfully creamy and flavorful.
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Onion Soup
INGREDIENTS
- 2 tablespoons unsalted butter
- 4 medium onions 6 oz each, sliced into thin rounds
- Pinch salt
- 2 tablespoons all-purpose flour*
- ½ cup dry white wine
- 1 quart beef broth not low-sodium
- ⅛ teaspoon black pepper
- ¼ teaspoon dried thyme
INSTRUCTIONS
- Heat the butter in a large saucepan over medium heat, about 4 minutes. Add the onions with a pinch of salt and patiently cook, stirring often, until caramelized, 15-20 minutes. If the pan becomes too dry during cooking, add a splash of water (1-2 tablespoons).
- Add the flour and mix with a wooden spoon about 1 minute, until it starts to brown.
- Add the wine. Mix well. Cook about 2 minutes, until most of the wine evaporates.
- Add the beef broth, the black pepper, and the dried thyme. Bring to a boil over high heat. Reduce the heat to medium-low and simmer, uncovered, stirring often, until the soup is noticeably thicker, about 20 minutes. Serve immediately.
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NOTES
NUTRITION PER SERVING
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Vered DeLeeuw, LL.M., CNC, has been following a low-carb real-food diet and blogging about it since 2011. She's a Certified Nutrition Coach (NASM-CNC), has taken courses at the Harvard School of Public Health, and has earned a Nutrition and Healthy Living Certificate from Cornell University. Her work has appeared in several major media outlets, including Healthline, HuffPost, Today, Women's Health, Shape, and Country Living. 