This easy onion soup is wonderfully rich and flavorful. The perfect choice for cold winter days, it's warm, tasty, and comforting.
I like to make a big pot of it because it keeps well in the fridge for several days.
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 pleasures, for sure - savoring 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 caramelized. That's where this soup gets its wonderful flavor.
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Ingredients
You'll only need a few simple ingredients to make this rich onion soup. The exact measurements are listed 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.
Instructions
Making this onion soup is easy! Scroll down to the recipe card for detailed instructions. Here are the basic steps:
- You start by patiently cooking the onions in butter until caramelized. This should take about 20 minutes.
- Now, mix in the flour and brown it.
- Next, add the wine and cook to reduce it.
- Add the beef broth and the spices and simmer until the soup is thickened, about 20 minutes.
Expert tip
Be sure to cook the onions slowly and patiently over medium heat until they are beautifully caramelized. This is where the soup gets its rich flavor and color. Don't attempt to shorten the process by turning the heat higher than medium!
Frequently asked questions
I do enjoy French onion soup, but I actually dislike the thick slab of melted cheese that often lays on top of it. So I make mine without it.
If you enjoy cheese in your soup, you could simply serve this soup with grated gruyere cheese on the side.
Indeed, this is not a gluten-free recipe, nor is it low-carb. I use a small amount of white flour to thicken the soup.
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.
I typically use yellow onions, but white onions should work too. I don't recommend using red onions in this recipe.
Variations
I love this recipe as is and almost always make it as written. But in case you'd like to vary the basic recipe, here are a few ideas for you:
- You can omit the wine if you wish, although it does enhance the soup's flavor.
- You can use chicken broth instead of beef broth.
- For a creamier soup, try stirring ¼ cup of room-temperature heavy cream into the soup once it's ready.
Serving suggestions
This soup is 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.
This soup is also good with almond flour cheese muffins or with almond flour cheese biscuits.
Storing leftovers
You can keep the leftovers in the fridge, in a sealed container, for 3-4 days. Gently reheat them in the microwave, covered, on 50% power.
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Recipe card
Rich 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 for about 1 minute, until it starts to brown.
- Add the wine. Mix well. Cook for about 2 minutes, until most of the wine evaporates.
- Add the beef broth, black pepper, and 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
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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. 