Lightened-Up French Onion Soup
A beloved French classic reimagined, this Lightened-Up French Onion Soup delivers all the deep, savory flavors of perfectly caramelized onions and rich beef broth, topped with a hint of bubbly Gruyère, without the heavy calorie count.
For 4 servings
**Prepare Onions:** Peel and thinly slice the yellow onions. Aim for uniform thickness (about 1/8 inch) for even cooking. A mandoline can be helpful here.
**Caramelize Onions:** In a large, heavy-bottomed pot or Dutch oven, melt the butter with the olive oil over medium-low heat. Add the sliced onions and a pinch of salt. Cook slowly, stirring occasionally, for 30-40 minutes, or until the onions are deeply golden brown, very soft, and reduced in volume. Do not rush this step; true caramelization is key to flavor.
**Add Aromatics & Deglaze:** Stir in the minced garlic and cook for 1 minute until fragrant. Pour in the dry sherry (or white wine) and scrape the bottom of the pot with a wooden spoon to release any browned bits (fond). Let it simmer for 2-3 minutes until the liquid has mostly evaporated.
**Simmer Soup:** Add the low-sodium beef broth, dried thyme, and bay leaf to the pot. Bring the mixture to a gentle simmer, then reduce the heat to low, cover, and let it cook for at least 20 minutes to allow the flavors to meld. Season with kosher salt and freshly ground black pepper to taste.
**Prepare Toasts:** While the soup simmers, preheat your oven broiler. Arrange the baguette slices on a baking sheet and toast them lightly under the broiler for 1-2 minutes per side, until golden. Set aside.
**Assemble & Broil:** Ladle the hot soup into individual oven-safe bowls. Place one toasted baguette slice on top of each bowl of soup, then sprinkle generously with shredded Gruyère cheese. Place the bowls on a baking sheet (to catch any drips) and broil for 2-4 minutes, or until the cheese is melted, bubbly, and lightly golden brown. Watch carefully to prevent burning.
**Serve Immediately:** Carefully remove the bowls from the oven using oven mitts. Let them cool for a minute or two before serving, as the bowls will be extremely hot.
What to keep in mind.
4 tips from the recipe — small details that make a real difference to the final dish.
- 1**Patience is Key:** The most crucial step is caramelizing the onions. Don't try to rush it by increasing the heat; low and slow yields the best depth of flavor.
- 2**Quality Broth Matters:** Since broth is a primary component, use the best quality low-sodium beef broth you can find. This significantly impacts the final taste.
- 3**Oven-Safe Bowls:** Ensure your soup bowls are genuinely oven-safe and can withstand high broiler temperatures to prevent cracking.
- 4**Uniform Slicing:** Using a mandoline or a very sharp knife to slice onions thinly and uniformly ensures they cook evenly and caramelize beautifully.
Adapt it for your goals.
Vegetarian Version
Substitute beef broth with a rich, dark mushroom or vegetable broth. Omit the cheese or use a plant-based Gruyère alternative for a fully vegan option.
Heartier AdditionHeartier Addition
For a more substantial soup, sauté sliced cremini mushrooms along with the onions. They add an extra layer of umami and texture.
Cheese AlternativesCheese Alternatives
While Gruyère is traditional, you can experiment with other good melting cheeses like Emmental, Provolone, or even a sharp white cheddar for a different flavor profile.
Why this is on our healthy list.
Digestive Health
Onions are rich in prebiotics, which feed beneficial gut bacteria and can improve digestive health.
Antioxidant Rich
Onions contain various antioxidants, including quercetin, which help combat oxidative stress and inflammation in the body.
Lower Calorie Comfort
By minimizing butter and using a lean broth, this recipe offers the comforting flavors of French onion soup with significantly fewer calories and saturated fat.
Frequently asked questions
Yes, the soup base (without the bread and cheese topping) can be made 2-3 days in advance and stored in the refrigerator. Reheat gently on the stovetop before proceeding with the topping and broiling steps.
