Heat the olive oil in a pot over medium-high heat. Sauté the onions until fragrant. Add the cauliflower florets, curry powder, turmeric, salt and ground pepper. Give it a good stir to ensure all of the spices evenly coat the cauliflower. Then, pour in half of the coconut milk and hot water, and allow to simmer covered over medium heat for about 15 minutes.
Once the cauliflower has cooked to a point where they can easily be mashed with a fork but are not total mush, take the pot off the stove and purée the soup with a hand blender. Add the rest of the coconut milk, while reserving about a tablespoon to dress the soup. Bring to a gentle boil. Verify the salinity of the soup and add additional salt if necessary.
When serving, drizzle a few drops of the remaining coconut milk and garnish with a shake of ground black pepper and red chili powder.