Thai Sweet Potato Lentil Soup with Coconut and Lemongrass

Thai sweet potato lentil soup with coconut and lemongrass delivers fragrant, warming comfort with sweet, spicy and tangy flavors that transport you straight to a Thai street market. This easy vegan soup is ready in 35 minutes, costs less than $10 to make, and the leftovers taste even more flavorful the next day as the lemongrass infuses deeper. It’s perfect for meal prep and will fill your kitchen with the most incredible aroma.

What Makes This Vegan Thai Soup Special

The combination of creamy coconut milk, aromatic lemongrass and Thai red curry paste creates complex flavor that tastes like you’ve been simmering it for hours.

Red lentils break down completely as they cook, naturally thickening the soup into a silky, velvety texture without any blending required. Sweet potatoes add natural sweetness and creaminess while providing vitamins that support healthy vision and immune function.

Fresh lemongrass stalks infuse the broth with bright, citrusy notes that lift all the other flavors; you smash them first to release their aromatic oils. This is a one-pot meal that’s both nourishing and exotic enough to feel special on a weeknight.

Ingredients

You need Thai aromatics, red lentils and sweet potatoes for this fragrant fall soup recipe.

• 2 tablespoons coconut oil
• 1 large onion, diced
• 3 garlic cloves, minced
• 2 tablespoons fresh ginger, grated
• 2-3 tablespoons Thai red curry paste (adjust to heat preference)
• 1 cup red lentils, rinsed
• 2 medium sweet potatoes, peeled and cut into 1/2-inch cubes (about 3 cups)
• 1 stalk lemongrass, tough outer layers removed, cut into 3-inch pieces and smashed
• 2 kaffir lime leaves (or zest of 1 lime)
• 1/2 teaspoon turmeric
• 4 cups vegetable broth
• 1 can (14 oz/400ml) coconut milk
• 1 tablespoon soy sauce or tamari
• 1 tablespoon lime juice
• 1 teaspoon brown sugar or maple syrup
• Salt to taste
• Fresh cilantro for garnish
• Red pepper flakes (optional)
• Lime wedges for serving

Kaffir lime leaves add authentic Thai flavor; find them frozen at Asian markets if not fresh.

How to Make This Healthy Vegetarian Soup

1. Prepare the lemongrass by removing the tough outer layers and cutting the tender lower bulb into 3-inch pieces; use the back of a knife or a meat mallet to smash them to release the aromatic oils.
2. Heat the coconut oil in a large pot over medium heat.
3. Add the diced onion and sauté for 5-6 minutes until softened and translucent.
4. Stir in the garlic and ginger; cook for 1-2 minutes until fragrant.
5. Add the Thai red curry paste and stir constantly for 1 minute to toast the spices and release their flavor.
6. Add the rinsed red lentils and stir to coat them in the curry paste mixture.
7. Add the cubed sweet potatoes, smashed lemongrass pieces, kaffir lime leaves and turmeric.
8. Pour in the vegetable broth and stir to combine everything.
9. Bring to a boil, then reduce heat to medium-low, cover and simmer for 20-25 minutes until the lentils are completely soft and the sweet potatoes are tender.
10. The red lentils will break down naturally, thickening the soup and turning it creamy.
11. Remove the lemongrass pieces and kaffir lime leaves; they’ve infused their flavor but are too fibrous to eat.
12. Stir in the coconut milk, soy sauce, lime juice and brown sugar.
13. Simmer for another 5 minutes to let the flavors meld.
14. Taste and adjust seasoning with more salt, lime juice or curry paste if needed.
15. Serve hot garnished with fresh cilantro, a drizzle of coconut milk and lime wedges on the side.

Substitutions and Variations

Butternut squash can replace sweet potatoes for a similar sweet, creamy texture. For a chunkier soup, use brown or green lentils instead; they’ll hold their shape but need to cook for 30-35 minutes.

If you can’t find lemongrass, substitute with 2 teaspoons of lemongrass paste or the zest of 2 lemons plus 1 tablespoon lemon juice. Thai green curry paste works instead of red for a different but equally delicious flavor profile.

Add vegetables like bell peppers, snap peas or bok choy in the last 5 minutes for extra nutrition and crunch. For more protein, stir in chickpeas or cubed firm tofu at the end.

Make it extra creamy by using full-fat coconut milk and adding an extra 1/2 cup. A handful of spinach or Thai basil stirred in at the end adds fresh, bright color.

What to Serve With This Coconut Lentil Soup

Jasmine rice or coconut rice on the side soaks up the flavorful broth and makes the meal more filling.

Crispy spring rolls or vegetable samosas add crunchy texture that contrasts beautifully with the creamy soup.

Thai-style cucumber salad with rice vinegar and chili provides a cool, refreshing counterpoint to the warm, spicy soup.

More Easy Lentil Soup Recipes

My Moroccan lentil soup with harissa and lemon has similar warming spices and bright citrus but with North African flavors instead of Thai.

Try my yellow lentil curry with coconut milk and Thai basil for another Thai-inspired dish with similar ingredients but thicker, dal-like consistency.

For a completely different take on red lentils, make my Turkish red lentil soup with mint oil drizzle which is silky and comforting with Middle Eastern flavors.

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