Home » Keto Soup Recipes » Onion Soup Recipe
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This onion soup is rich and flavorful. The perfect choice for cold winter days, it's warm, tasty, and comforting.
I like to make a big pot because it keeps well in the fridge for several days. I simply reheat it in the microwave.
A hot bowl of soup on a cold day (or a mug of hot chocolate) is one of life's pleasures. I make many soup recipes, including vegetable beef soup, cabbage soup, and cauliflower soup.
I enjoy them all, but this onion soup is especially good. It's rich, flavorful, and comforting. The secret is to saute the onions slowly and patiently until they are caramelized. That's where this soup gets its wonderful flavor.
Jump to:
- Ingredients
- Variations
- Onion Soup Instructions
- Expert Tip
- Recipe FAQs
- Serving Suggestions
- Storing Leftovers
- More Soup Recipes
- Foodie Newsletter
- Recipe Card
Ingredients
You'll only need a few simple ingredients to make this recipe. 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 onions are easier to caramelize and will yield a more flavorful soup.
- 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 excellent, but store-bought is fine too. It's also OK 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, taste and decide if you want to add more salt.
Variations
- 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. I tried both versions and liked both.
- For a creamier soup, I sometimes stir ¼ cup of room-temperature heavy cream into the soup once it's ready.
Onion Soup Instructions
Scroll down to the recipe card for detailed instructions. Here are the basic steps for making this recipe:
Slice the onions and separate the slices into rings. Patiently cook the onions in butter until caramelized, about 20 minutes.
Mix in the flour and brown it.
Add the wine and cook to reduce it.
Add the beef broth and spices; simmer until the soup thickens, about 20 minutes.
Divide into bowls and serve.
Expert Tip
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 the medium setting.
Recipe FAQs
Should I add cheese to the soup?
I enjoy French onion soup but dislike the thick slab of melted cheese that often lies 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.
Can you suggest an alternative to white flour?
Indeed, this is not a gluten-free or low-carb recipe. I use a small amount of white flour to thicken the soup.
If you must avoid gluten, use a cornstarch slurry at the end of cooking. Stir in one tablespoon of cornstarch mixed with 1 ½ tablespoons of cold water and cook for 1-2 more minutes or until the soup slightly thickens.
What type of onions should I use?
I typically use yellow onions, but white onions work too. I don't recommend using red onions in this recipe.
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 any of the following items on the side:
- Almond flour cheese muffins
- Almond flour cheese biscuits
- Almond flour bread
- Keto crackers
- Cheese crackers
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, at 50% power.
More Soup Recipes
- Egg Drop Soup
- Cream of Broccoli Soup
- Butternut Squash Soup
- Easy Tomato Soup
Recipe Card
4.99 from 188 votes
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Rich Onion Soup
This easy onion soup is wonderfully rich and flavorful. The perfect choice for cold winter days, it's warm, tasty, and comforting.
Prep Time10 minutes mins
Cook Time50 minutes mins
Total Time1 hour hr
Course: Soup
Cuisine: French
Servings: 4 servings
Calories: 175kcal
Author: Vered DeLeeuw
Ingredients
- 2 tablespoons unsalted butter
- 4 medium onions 6 ounces 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. 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.
Video
Notes
- This is not a gluten-free or low-carb recipe.
- I typically use yellow onions in this recipe, but white onions work too. I don't recommend using red onions in this recipe.
- 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 the medium sertting!
- You can keep the leftovers in the fridge, in a sealed container, for 3-4 days. Gently reheat them in the microwave, covered, at 50% power.
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Nutrition per Serving
Serving: 0.25recipe | Calories: 175kcal | Carbohydrates: 19g | Protein: 5g | Fat: 7g | Saturated Fat: 3g | Sodium: 616mg | Fiber: 3g | Sugar: 8g
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About the Author
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. Click to learn more about Vered.
Reader Interactions
Comments
Jaime
It is very nice, I just add a spoon of cheese and got cheesy.Reply
Vered DeLeeuw
I'm so glad you like this onion soup, Jaime! Thanks for sharing how you serve it.
Reply
Katie
This is so delicious! This is my second time making this recipe and both times it's turned out amazing. It does take a bit longer than 20 minutes to carmelize the onions. It's worth the wait! We eat it as is, no need for bread or cheese.Reply
Vered DeLeeuw
Yay! I'm so glad you like this recipe, Katie! Many thanks for taking the time to leave a comment. I appreciate it.
Reply
Janna Carr
This recipe is rich indeed! So flavorful. I had to cook my onions a little longer than 20 minutes to caramelize, took more like 45. I also was out of beef stock, so I used chicken and then threw in 2 beef bouillon cubes. Also threw in a couple of bay leaves and it was so delicious. Ate it without cheese and some sourdough bread to dip! So good!Reply
Vered DeLeeuw
I'm so glad you enjoyed this soup, Janna! Thank you for your comment.
Reply
Ann
I don't have wine or beef or chicken broth. I would like to know if I can use milk or water. I do have seasonings and red wine vinegar.
Reply
Vered DeLeeuw
Hi Ann,
You can omit the wine, but beef or chicken broth is essential to the success of this recipe and to the richness of the soup.Reply
