Heat oil in large saucepan set over medium heat; cook onion, stirringoccasionally, for about 5 minutes or until softened. Add garlic, curry paste and ginger; cook, stirring, for about 1 minute or until fragrant.
Add cauliflower, potato, vegetable broth, coconut milk, salt and pepper; bring to boil. Reduce heat; simmer for 20 to 30 minutes or until cauliflower is tender.
Remove from heat; purée until smooth using immersion blender.Stir in lime juice. Sprinkle with cilantro.
Tip: If necessary, purée the soup in batches in a blender.