Preparation Heat oil in heavy large pot over medium-high heat. Add onion and sauté until translucent, stirring often, about 5 minutes. Add sugar and curry powder; stir 1 minute. Add cauliflower and potatoes; stir 1 minute. Add broth and bring to boil. Reduce heat to medium, cover, and simmer until vegetables are tender, about 35 minutes. Working in batches, puree soup in blender. Return soup to same pot and bring to simmer. Season with salt and pepper. Ladle soup into bowls; top with yogurt and some mint.
Preparation Heat oil in heavy large pot over medium-high heat. Add onion and sauté until translucent, stirring often, about 5 minutes. Add sugar and curry powder; stir 1 minute. Add cauliflower and potatoes; stir 1 minute. Add broth and bring to boil. Reduce heat to medium, cover, and simmer until vegetables are tender, about 35 minutes. Working in batches, puree soup in blender. Return soup to same pot and bring to simmer. Season with salt and pepper. Ladle soup into bowls; top with yogurt and some mint.