Heat olive oil in a large pot over medium heat.
Add the chopped onion and sauté for 5 minutes until translucent.
Add the minced garlic and grated ginger, and cook for another 1 minute until fragrant.
Stir in the ground turmeric and ground cumin, cooking for 30 seconds to release their aroma.
Add the cauliflower florets to the pot and stir to coat with the spices.
Pour in the vegetable broth and bring the mixture to a boil.
Reduce heat to low, cover, and simmer for 15 minutes until the cauliflower is tender.
Remove the pot from heat and use an immersion blender to puree the soup until smooth. Alternatively, carefully transfer the soup in batches to a blender and puree until smooth.
Return the pureed soup to the pot and stir in the coconut milk, salt, and black pepper.
Heat the soup gently over low heat for 3-5 minutes until warmed through, stirring occasionally.
Ladle the soup into bowls and garnish with fresh cilantro leaves before serving.