Heat the coconut oil in a Dutch oven or saucepan. Add the onions, garlic, and ginger and cook until fragrant, about 2 minutes.
Add the sweet potatoes, carrots, and seasonings, stir until coated and add the broth. Bring to a boil and reduce to a simmer. Simmer until vegetables are tender, 10-15 minutes.
Transfer the soup to a blender and blend until smooth, pureeing in batches if necessary.
Add back to the pot, add the coconut milk and lime juice and simmer until heated through.