This vegan red lentil soup is exactly what you need on a chilly day. It's full of healthy vegetables, like carrots, celery, and leafy greens. And, it's cozy and comforting thanks to the potatoes and silky red lentils. This soup is easy to make and cooks quickly. We love to make a big pot at the beginning of the week, so we can reheat the soup for quick weekday lunches and dinners.
Why you'll love this recipe
- Healthy & delicious: This delicious vegan soup uses protein-rich lentils and colorful veggies. It's a yummy and nourishing meal that'll keep you satisfied.
- Cooks fast: Ready in just over 30 minutes! Red lentils cook quickly, but they do take a bit longer when cooked with acidic ingredients like tomatoes. So, this recipe cleverly adds the tomatoes near the end, to cut down on cooking time.
- Meal prep friendly: This soup can be made in advance for quick weeknight meals. Or, make a double batch and freeze extras!
Ingredients (and substitutes)
This vegan red lentil soup is made with mostly pantry ingredients. The key ingredients for this recipe are:
- Dried red lentils: Red lentils are quick-cooking, inexpensive, and a healthy source of plant-based protein. They make for a delicious and satisfying soup! (Learn more about lentils—including if they're actually gluten-free and what to watch for).
- Fire roasted tomatoes: Canned fire-roasted tomatoes are a quick and easy way to add depth of flavor. If you can't find diced or crushed fire-roasted tomatoes, you can use canned whole tomatoes instead.
- Potatoes: We like to use yellow potatoes in this soup, such as Yukon Gold. Their skins are thin so you don't need to peel them. But, you can also substitute another type of potato if you prefer.
- Swiss chard: We use both the leaves and stems (thinly sliced). Instead of Swiss chard, you could use kale or spinach.
- Thyme: If you can, use fresh thyme leaves for the best flavor. Otherwise, you can substitute with dried thyme instead. Dried thyme is more potent than the fresh stuff, so you'll need less (one-third of the amount, see recipe card for full details).
- Dried cumin: This soup keeps things simple and doesn't call for a lot of different spices. This recipe calls for adding the dried cumin directly into the hot olive oil. This process is called "blooming", and it helps to amplify the flavor of the spices.
Find the recipe card below for the complete recipe, including all ingredients and instructions.
About red lentils
Of all the different kinds of lentils out there, we choose red lentils when we're short on time. Red lentils cook quickly: usually in about 15 minutes. When lentils are cooked in acidic ingredients, it can take longer for them to soften. So, to keep the cooking time down, this recipe adds the acidic ingredients at the end, after the lentils have softened.
Red lentils are a source of plant-based protein, iron, and folate (source). Lentils are considered an incomplete protein, because they don't contain all the essential amino acids. But don't worry—if your diet includes whole grains, the combination will make a complete protein. And while you don't need to pair them in the same meal...it is a good excuse to serve some crusty bread with your lentil soup!
Red lentils are well suited for soups—like this vegan red lentil soup and our Curried Pumpkin and Lentil Soup recipe. But, you can also use red lentils in places you don't expect it—like these healthy gluten free & vegan Morning Glory Breakfast Muffins. If you have other creative ways to cook with red lentils, we'd love to hear about them!
Learn more about lentils here—including some important considerations if you're gluten-free.
Storage and reheating tips
Refrigerating the soup
This recipe makes a big batch, so we usually refrigerate extra soup in an airtight container. You'll likely need to thin the soup the next day, either with a bit of vegetable stock or water. The soup can be reheated on the stove, over medium heat, covered with a lid.
Freezing the soup
This soup is freezer-friendly. When freezing a soup like this, we'll usually hold off on adding the tender greens until it's time to eat. If you'd like to do this too, then make the recipe as directed for everything except adding the Swiss chard. Then, stir in the Swiss chard when you are warming the soup to eat. But, this is personal preference and you can definitely freeze the soup with the greens if you prefer!
There are many methods to freezing and defrosting soup. We let the soup cool, then transfer it to a freezer bag and freeze on its side so it's as flat as possible. We find it defrosts faster and stays nice and organized in the freezer. But again, do what works best for you.
To reheat frozen soup, let it defrost (either in the fridge overnight or in a cold water bath). Transfer soup to a pot and reheat on the stove.
Vegan Red Lentil Soup
- 4 tablespoons extra virgin olive oil, divided
- 1 lb yellow onions, diced (about 3 cups)
- 2 carrots, diced
- 2 ribs celery, diced
- 2 teaspoons cumin
- 4 cloves garlic, minced
- 1 tablespoon fresh thyme leaves (or
1 teaspoon dried)
- 1 teaspoon fine sea salt
- 5 cups vegetable broth
- 12 oz yellow potatoes, diced (about 2 cups, see note 1)
- 1½ cups dry red lentils (rinsed and picked over)
- 1 (28 fl oz/796 ml) can fire-roasted diced tomatoes (see note 2)
- 1 bunch Swiss chard, chopped (about 10 oz/283g, see note 3)
- 1 tablespoon red wine vinegar (see note 4)
- Saute vegetables: Warm 2 tablespoons of the olive oil in a large Dutch oven or pot over medium heat. Add onion and cook, stirring occasionally, until golden brown around the edges, 8 to 10 minutes. Add carrots and celery, cook, stirring occasionally, for 2 minutes to soften.
- Add spices: Use a stirring spoon to push the vegetables to the edges of the pot. Pour the remaining 2 tablespoons olive oil into the middle of the pot, then sprinkle cumin into oil. Once it starts to sizzle, add garlic, thyme, and salt. Cook, stirring frequently, until the garlic is fragrant, 1 to 2 minutes
- Simmer: Pour in the vegetable broth and use a stirring spoon to loosen any brown bits from the bottom of the pot. Add the potatoes and red lentils. Stir to mix. Cover with a lid, increase heat to medium high, and bring to a boil. Once boiling, reduce the heat to maintain a simmer with the lid slightly ajar. Cook, stirring occasionally, until the lentils are soft and potatoes are tender, about 15 minutes.
- Finish and season: Stir in the tomatoes, then bring the mixture back to a boil (keep the lid slightly ajar and increase heat slightly). Once boiling, stir in the Swiss chard to wilt the leaves. Remove from heat. Add red wine vinegar. Taste and season with more salt if needed (see note 5).
- Potatoes: If using yellow potatoes, you don't need to peel them. You can substitute with other potatoes if you prefer (such as red potatoes or Russet).
- Fire-roasted tomatoes: Or, 2 smaller 14 fl oz/398 ml cans. You can use crushed fire-roasted tomatoes instead of diced. Fire-roasted tomatoes add an extra depth of flavor, but if you can't get them, you can substitute whole peeled San Marzano tomatoes from a can (crush them with your hands as you add the tomatoes and their juices to the pot).
- Swiss chard: We use the leaves and stalks (slicing the stalks thinly so that they soften at a similar time as the leaves). But if you're not a fan of the stalks, leave them out. Instead of Swiss chard, you could substitute thinly sliced kale or spinach.
- Red wine vinegar: A small splash of vinegar (acid) really helps brighten up flavors in dishes. We prefer red wine vinegar in this soup, but in a pinch you could use a squeeze of fresh lemon or white wine vinegar instead.
- Thinning soup: If the soup is too thick for your liking, you can thin it with extra vegetable broth or water. When reheating soup the next day, you'll likely want to thin it slightly with a splash more liquid.
- Storage and reheating: Refrigerate extra soup in an airtight container. Reheat the soup in a pot on the stove, over medium heat, covered with a lid. You may want to add a splash of water or vegetable stock to thin. This soup can also be frozen. Defrost frozen soup (either in the fridge overnight or in a cold water bath), then reheat on the stove as directed. When freezing soups, we prefer to hold off on adding tender greens (in this case, the Swiss chard)—then add the greens when reheating on the stove...but this is up to you!
- Yield: makes about 12 to 13 cups of soup.