Heat olive oil in a large pot over medium heat.
Add diced onion and sauté for 5 minutes until translucent.
Add minced garlic and grated ginger; cook for 1 minute until fragrant.
Stir in ground turmeric, ground cumin, ground black pepper, and sea salt; cook for 1 minute to toast the spices.
Add chopped cauliflower florets 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 and fresh lemon juice.
Heat the soup gently over low heat for 3-5 minutes until warmed through, but do not boil.
Taste and adjust seasoning if needed.
Serve hot, garnished with chopped fresh cilantro.