Boil the potatoes in salted water until not quite tender, about 15 minutes.
Prepare the sauce by melting the sugar in a heavy saucepan over medium heat. In a short time the sugar will begin to turn to a light golden brown. Stir to prevent burning. When light brown syrup is formed, immediately add the corn syrup, followed by the water. Blend thoroughly.
Allow to cool for just a moment and then stir in the pecans, butter, salt and vanilla extract.
Place the potatoes in a greased baking dish.
Pour some of the sauce over the potatoes and bake at 375 degrees F for about 20 minutes.
The sauce is very rich, and you may want to save some for over ice cream.