In a large soup pot, heat 2 tbsp olive oil over medium heat. Add carrots, celery, onion and 1 tsp salt, cook for 3-5 minutes, until onion is translucent and vegetables begin to soften.
Add garlic, tomato paste, cumin, coriander and chili flakes. Sauté for another 2 minutes, until tomato paste begins to caramelize and turn a deep red and the spices are fragrant.
Add the water, lentils, bay leaves and remaining salt to the pot. Cover and simmer for 25-30 minutes, until lentils are tender. Remove bay leaves, stir in lemon juice and remaining olive oil. Serve with parsley sprinkled on top.