In a soup pot, heat the olive oil (over medium heat), then add in the onion, carrot, cayenne pepper, coriander, cumin, and turmeric. Cook the vegetables until they are softened.
Add the cauliflower and cilantro and cook for 1 to 2 minutes, stirring often.
Pour in the vegetable stock and bring the mix to a boil. Lower heat, cover, and simmer for approximately 10 to 15 minutes (or until cauliflower is soft).
Using a food processor or blender, process the soup until smooth. Add in lemon juice, stir, then salt and pepper to taste.
Plate the soup, sprinkle with additional cayenne pepper powder, then serve.