Heat oil in a large pot over medium heat. Saute onion until tender and translucent. Stir in the curry powder. Add the chopped carrots, and stir until the carrots are coated. Pour in the vegetable broth, and simmer until the carrots are soft, about 20 minutes.
Transfer the carrots and broth to a blender, and puree until smooth. Pour back into the pot, and thin with water to your preferred consistency.
