Heat olive oil in a large pot over medium heat.
Add onion and cook for 5 minutes, until soft and translucent.
Add garlic, carrot, and celery; cook for 3 minutes, stirring often.
Sprinkle in cumin, turmeric, coriander, salt, and pepper. Stir to coat veggies.
Pour in vegetable broth and bring to a boil.
Add lentils, reduce heat to a simmer, and cook for 25 minutes, until lentils are tender.
Stir in coconut milk and cook for an additional 5 minutes, simmering gently.
Remove from heat, add lemon juice, and stir well.
Garnish with fresh cilantro and serve hot.