Sauté the Aromatics: Heat a large soup pot over medium heat and add a tablespoon of olive oil. Add the chopped onion and garlic. Sauté for about 2 minutes until the onion turns translucent. Then add the diced carrot and saute for about a minute or until the carrots are a bit soften.
Add Spices: Stir in the ground cumin, turmeric, and cayenne pepper (if using). Cook for an additional 1-2 minutes to toast the spices, releasing their flavors.
Add Lentils and Liquid: Add the rinsed red lentils, vegetable broth, and water to the pot. Stir well to combine. Season with salt and pepper to taste.
Simmer: Bring the mixture to a boil, then reduce the heat to low and cover. Let the soup simmer for about 18 to 20 minutes or until the lentils are tender and cooked through.
Blend or Mash: You can choose to leave the soup chunky or use an immersion blender to partially blend the soup for a smoother consistency. If using a blender, allow the soup to cool slightly before blending in batches. Stir in the fresh lemon juice, then add any additional salt and pepper to taste, if required.
Serve: Serve the red lentil soup in bowls and garnish with fresh cilantro or parsley. You can also drizzle a bit of olive oil on top for extra richness.
