
This simple Cauliflower Leek soup is rich in cancer-fighting compounds from cauliflower and leeks, and white sweet potatoes add lots of fiber. If you can't find them, substitute any white potato. This soup has a smooth, velvety texture with little fat and no dairy. For a richer soup, add Greek yogurt or creme fraiche while you’re pureeing the soup.
Heat 1 tablespoon of the olive oil in a large pot. Add leek and cook for 2 to 3 minutes until just softened, being careful not to brown.
Add cauliflower, potatoes and broth. Bring to a boil, reduce heat and simmer, covered, until cauliflower and potatoes are tender, 12 to 15 minutes.
While soup is cooking, combine tarragon, basil and remaining 1/4 cup oil in a blender and puree until smooth.
Add soup to a food processor and puree till smooth and creamy.
Season to taste with salt and white pepper.
Divide soup between individual bowls and drizzle with tarragon oil. Serve immediately.