Step 1 Heat the oil in a large saucepan over medium heat. Add the garlic, leeks and carrots and cook until the leeks are softened, 10 minutes. Add the cumin, cayenne pepper and chicken broth. Let simmer, covered, until the carrots are very tender, 15 to 20 minutes.
Step 2 Puree the soup in a blender in batches until smooth.
Step 3Serve warm or cold with a dollop of creme fraiche and a pinch of chopped cilantro.