Heat a Dutch oven or soup pan over medium-high heat. Add the olive oil and let heat. Add the onion and curry paste and cook, stirring occasionally, for 3 minutes. Add the cauliflower and broth and raise heat to high. Bring to a boil, cover pot, and let simmer for 20 minutes or until the cauliflower is tender. Stir in the coconut milk.
Blend the soup until smooth. Return to the pot to heat. Season to taste with salt and pepper.