1. Preheat oven to 325°.
2. Coat an 8-inch metal cake pan with high sides with canola oil, tipping to fully coat.
3. Combine granulated sugar and water in a small heavy saucepan over medium-high heat; cook for 5 minutes or until golden. Immediately pour into prepared pan, tipping quickly until caramelized sugar coats bottom of pan.
4. Place sweet potato and next 7 ingredients (through eggs) in a blender; process until smooth. Add milk; process just until blended. Pour mixture over caramel in pan. Place pan in a 13 x 9-inch glass or ceramic baking dish; add hot water to dish to a depth of 1 inch.
5. Bake at 325° for 1 hour or until a knife inserted in center comes out clean. Remove pan from water. Cool completely on a wire rack. Cover and chill for 8 hours or overnight. Invert flan onto a platter, and cut into 8 wedges. Drizzle any remaining caramel syrup over flan.