Prepare the ingredients: Rinse the lentils under cold water and chop the onion, garlic, and any optional vegetables (carrots, etc.).
Sauté the aromatics: In a large pot, heat the olive oil over medium heat. Add the chopped onion and sauté for 4-5 minutes until soft. Add the minced garlic and cook for another 1 minute.
Spice it up: Add the ground cumin, ground coriander, and ground turmeric (if using). Stir well and cook for about 1 minute until fragrant.
Add lentils and broth: Stir in the lentils, then add the vegetable broth (or water). Bring to a boil, then reduce the heat to a simmer.
Cook the soup: Cover and simmer for 20-30 minutes, or until the lentils are tender and the soup has thickened.
Season and blend: Add salt and pepper to taste. If you prefer a smoother texture, use an immersion blender to partially or fully blend the soup.
Finish with lemon: Stir in the lemon juice and adjust the seasoning if needed.
Serve: Ladle the soup into bowls. Garnish with fresh parsley and a drizzle of olive oil. Serve with toasted pita bread or any preferred side.