Heat oil in a Dutch oven. Add onion, and sauté 3 to 4 minutes or until tender. Add curry powder, 1/4 teaspoon salt, cumin, and cinnamon; cook 2 minutes. Slowly stir in chicken broth; bring to a boil. Add carrots; bring to a boil. Reduce heat, and simmer, covered, 8 to 10 minutes or until carrots are tender. Add 1/2 cup water and 1/4 teaspoon salt.
Place soup in batches in a blender or food processor; process until smooth. 3. Return mixture to Dutch oven. Stir in 1/2 cup water and coconut milk. Cook over medium heat 2 to 3 minutes.