Parboil sweet potatoes for about 10 minutes. Drain, peel and cut into strips. Mix egg with water and beat throughly. Seperate crushed corn flakes in two seperate bowls, making two half cups each. Flour may be substitued for one of the bowls of flakes. Dip the cut potatoes in the flour or crushed flakes, then in the egg mixture and then again in the other bowl of crushed flakes. Deep fry in oil (375 to 385 degrees) until browned. Drain on absorbent paper and sprinkle with salt. A mixture of cinnamon and sugar could also be used for a sweet tastse.