Heat the olive oil in a large pot over medium heat. Add the onion, garlic and carrots and cook, stirring frequently, for about 5 minutes.
Add the cinnamon, ginger and turmeric and stir into the vegetables for 30 seconds.
Add the red lentils, tomato paste and broth. Stir everything together well.
Bring the soup to a boil, then lower heat and simmer for 20 minutes, or until the lentils have softened and the soup has thickened.
Use an immersion blender to blend the soup in the pot until smooth. Alternatively, transfer in batches to a high speed blender and blend until very smooth.
Add salt to taste, and thin out with a little water or broth if desired.
Serve in bowls with a swirl of plain yogurt (I used Forager cashew yogurt) or coconut milk, chopped parsley or cilantro and perhaps a side of fresh bread for dipping.