A velvety, dairy-free tomato soup enriched with red lentils and fragrant fennel, this comforting bowl delivers deep flavor and a creamy texture without ever touching a blender. Pantry staples transform into a luxurious, slow-simmered soup that feels both rustic and refined.
Why You’ll Love This Recipe
Naturally creamy without any cream or blending
Budget-friendly pantry ingredients
Deep, slow-cooked flavor with minimal prep
Perfect for meal prep and reheating
Hearty enough to enjoy as a full meal
Elegant enough to serve guests
Seasonally versatile using canned tomatoes
Lentils melt into the soup for rich body and texture
Ingredients
(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)
2 tablespoons unsalted butter
2 tablespoons olive oil, plus extra for serving
4 garlic cloves, thinly sliced
1 large fennel bulb, thinly sliced
1 medium yellow or red onion, thinly sliced (or 2 large shallots)
1½ teaspoons kosher salt, plus more to taste
½ teaspoon freshly ground black pepper, plus more to taste
2 teaspoons fennel seeds
½ teaspoon crushed red pepper flakes, plus extra for serving
¾ cup red lentils, rinsed
1 (28-ounce / 796 g) can whole peeled tomatoes, crushed by hand
6 cups water, vegetable broth, or chicken broth
¼ cup sour cream, full-fat yogurt, or ¼ cup finely grated Parmesan cheese (optional, for serving)
Directions
In a large heavy-bottomed pot, heat the butter and 2 tablespoons olive oil over medium-high heat until melted and shimmering.
Add the sliced garlic, fennel, and onion. Season with 1½ teaspoons kosher salt and ½ teaspoon black pepper. Cook, stirring occasionally, for 12 to 15 minutes, until the vegetables are fully softened and lightly caramelized. Do not rush this step, as it builds the soup’s foundational flavor.
Stir in the fennel seeds and crushed red pepper flakes. Cook for 1 to 2 minutes, allowing the spices to toast and become fragrant.
Add the rinsed red lentils, crushed tomatoes, and 6 cups of water or broth. Stir well to combine.
Bring the mixture to a strong simmer over medium-high heat. Once simmering, reduce the heat to medium-low and cook uncovered for 45 to 50 minutes. Stir occasionally, especially during the final 15 minutes, encouraging the lentils and tomatoes to break down together.
The lentils should nearly disappear into the soup, creating a thick, creamy consistency. If the soup is thinner than desired, increase the heat slightly and continue simmering until thickened.
Taste and adjust seasoning with additional salt and pepper as needed.
Ladle into bowls and finish with a drizzle of olive oil, extra black pepper, and a pinch of red pepper flakes. Add a spoonful of sour cream, yogurt, or grated Parmesan if desired.
Make it fully vegan by using olive oil instead of butter and skipping dairy toppings.
Add 1 teaspoon smoked paprika for subtle smokiness.
Stir in a handful of chopped fresh parsley before serving for brightness.
Add ½ cup diced carrots with the onions for extra sweetness.
Blend partially if you prefer an ultra-smooth texture.
Increase red pepper flakes for a spicier version.
Top with homemade croutons for added crunch.
Storage/Reheating
Refrigerator: Store in an airtight container for up to 5 days. The soup will thicken as it sits.
Freezer: Freeze in sealed containers for up to 3 months. Leave space at the top for expansion.
Reheating: Warm gently on the stovetop over medium-low heat, stirring occasionally. Add a splash of water or broth if it has thickened too much. It can also be reheated in the microwave in 1-minute intervals, stirring between each.
FAQs
Can I use green or brown lentils instead of red?
Red lentils are best because they break down and create the creamy texture. Green or brown lentils will hold their shape and change the consistency.
Do I need to blend the soup?
No. The lentils naturally dissolve into the soup, creating a smooth, creamy result without blending.
Can I make this dairy-free?
Yes. Use olive oil instead of butter and skip dairy toppings or use plant-based yogurt.
Why are my lentils not breaking down?
They may need more cooking time. Continue simmering and stir occasionally to help them soften and dissolve.
Can I use fresh tomatoes?
Canned whole peeled tomatoes are recommended for consistent flavor, but very ripe fresh tomatoes can work if simmered longer.
Is this soup spicy?
It has mild warmth from red pepper flakes. You can adjust the heat to your preference.
Can I prepare this ahead of time?
Yes. The flavor deepens after a day, making it ideal for meal prep.
What pairs well with this soup?
Crusty bread, grilled cheese sandwiches, or a simple green salad complement it beautifully.
Can I double the recipe?
Absolutely. Use a larger pot and extend cooking slightly if needed to maintain a steady simmer.
How do I thicken the soup further?
Simmer uncovered for additional time to reduce liquid, or allow it to rest briefly as it naturally thickens while cooling.
Conclusion
Buttered Tomato Soup with Lentils and Fennel proves that simple pantry ingredients can create something deeply comforting and surprisingly luxurious. The slow caramelization of fennel and onion, the richness of tomatoes, and the creamy body from red lentils come together in a bowl that feels both nourishing and indulgent. Whether served plain or topped with a swirl of yogurt, this soup delivers warmth and satisfaction every time.
Buttered Tomato Soup with Lentils and Fennel is a velvety, slow-simmered soup made with caramelized fennel, tomatoes, and red lentils that naturally create a creamy texture without blending. Rustic yet refined, this comforting bowl is hearty, flavorful, and perfect for meal prep.
Ingredients
2 tablespoons unsalted butter
2 tablespoons olive oil, plus extra for serving
4 garlic cloves, thinly sliced
1 large fennel bulb, thinly sliced
1 medium yellow or red onion, thinly sliced (or 2 large shallots)
1 1/2 teaspoons kosher salt, plus more to taste
1/2 teaspoon freshly ground black pepper, plus more to taste
2 teaspoons fennel seeds
1/2 teaspoon crushed red pepper flakes, plus extra for serving
3/4 cup red lentils, rinsed
1 (28-ounce / 796 g) can whole peeled tomatoes, crushed by hand
6 cups water, vegetable broth, or chicken broth
Optional: 1/4 cup sour cream, full-fat yogurt, or finely grated Parmesan cheese for serving
Instructions
Heat butter and olive oil in a large heavy-bottomed pot over medium-high heat until melted.
Add garlic, fennel, and onion. Season with salt and pepper. Cook 12–15 minutes, stirring occasionally, until softened and lightly caramelized.
Stir in fennel seeds and crushed red pepper flakes. Cook 1–2 minutes until fragrant.
Add rinsed red lentils, crushed tomatoes, and water or broth. Stir well.
Bring to a strong simmer, then reduce heat to medium-low and cook uncovered for 45–50 minutes, stirring occasionally.
Allow lentils to break down fully, creating a thick, creamy texture. Simmer longer if needed to thicken.
Taste and adjust seasoning with additional salt and pepper.
Ladle into bowls and finish with olive oil, extra pepper, red pepper flakes, and optional dairy topping.
Notes
For a vegan version, use only olive oil and skip dairy toppings.
Add smoked paprika for subtle smokiness.
The soup thickens as it cools; add broth when reheating if needed.
Red lentils work best as they break down completely.
Store refrigerated up to 5 days or freeze up to 3 months.
