Description
This comforting French Onion Lentil Soup combines the rich caramelized sweetness of slow-cooked onions with hearty petite lentils, simmered in a low-sodium beef broth infused with thyme and bay leaf. Finished with toasted French bread topped with bubbling Gruyère cheese broiled to perfection, this dish offers a satisfying twist on the classic onion soup, perfect for a cozy meal.
Ingredients
Soup Base
- 2 Tbsp. butter
- 2 Tbsp. extra-virgin olive oil
- 3 large yellow onions (about 2 1/2 to 3 lbs.), peeled and thinly sliced
- 4 garlic cloves, minced
- 2 tsp. lower sodium tamari
- Kosher salt and cracked black pepper to taste
Lentils and Broth
- 1 cup petite lentils, such as French (Le Puy) lentils or black (Beluga) lentils
- 2 quarts (8 cups) low sodium beef broth (or beef stock)
- 6 to 8 sprigs fresh thyme (or 1 tsp. dried thyme)
- 1 bay leaf
- 2 Tbsp. sherry vinegar
Topping
- 8 to 12 (½-inch) slices French bread (from 1 baguette)
- 1 1/2 cups grated Gruyère cheese
Instructions
- Caramelize Onions: Start by melting butter and olive oil in a large Dutch oven or stock pot over medium heat. Add sliced onions and 1/2 teaspoon salt; cook, stirring every 5 minutes or so, until onions begin to caramelize. Lower the heat if the onions brown too quickly. This process takes about 40 minutes total. Stir in minced garlic and tamari during the final 2 minutes to enhance the flavor.
- Simmer Soup: Add the lentils, low sodium beef broth, thyme sprigs, bay leaf, and a few grinds of black pepper to the pot. Increase heat to bring the soup to a low boil. Reduce heat and gently simmer with the lid slightly ajar for about 30 minutes, until lentils are tender. Remove and discard bay leaf and thyme sprigs, then stir in the sherry vinegar. Taste and adjust salt and pepper as needed.
- Prepare and Broil Topped Soup: Preheat the broiler to high. Arrange ovenproof soup bowls on a baking sheet. Ladle hot soup into each bowl and top with slices of French bread. Generously sprinkle grated Gruyère cheese over the bread. Place the baking sheet under the broiler about 6 inches from the heat source and broil for 2 to 4 minutes until the cheese is melted and bubbly. Watch closely to prevent burning. Remove from oven and serve immediately while hot.
Notes
- Caramelizing onions slowly over medium to low heat develops rich flavor without burning.
- The choice of lentils is essential: French (Le Puy) or black (Beluga) lentils hold their shape well and complement the soup texture.
- Using low sodium broth allows better control over final seasoning.
- Sherry vinegar brightens and balances the deep sweetness from caramelized onions.
- Broil just long enough to melt and bubble the cheese for the perfect crunchy, creamy topping.
- If preferred, substitute beef broth with vegetable broth for a vegetarian variation (and adjust diet label accordingly).
