1. In a large pot, heat the olive oil over medium-high heat. Add the onion, carrot, celery, and sweet potato. Cook for 4 to 5 minutes, until the onion begins to soften.
2. Add the garlic, ginger, apples, and tomato. Cook for 3 to 4 minutes.
3. Add the curry powder, cumin, paprika, cinnamon, turmeric, cardamom, pepper, and thyme and mix well to combine.
4. Add the lentils and broth. Bring to a boil, then reduce the heat to medium-low and simmer for 30 minutes
5. Using a blender or an immersion blender, puree about three- quarters of the soup. Leave the rest of the soup chunky.
6. Return the pureed soup to the pot with the rest of the soup, if necessary.
7. Stir in the coconut milk. Season with salt and pepper.
8. Ladle the soup into bowls. Garnish with cashews and serve with naan bread.