Preheat oven to 400 F.
Place the 4 small sweet potatoes in a glass baking dish. Carefully add a 1" to 2" slit lengthwise down the center.
Pour the water into the glass baking dish around the sweet potatoes. This will create the "steam-bake" effect on the cooking.
Cover tightly with foil, pressing and pinching around the edges of the baking dish to create as best of a seal as you can.
Bake in the preheated oven for XX minutes, or until tender in the middle. Cooking time may depend on how thick the sweet potatoes are.
Let cool for 10 minutes, then carefully remove the sweet potatoes from the tray.
Option #1: Serve as is with toppings or butter.
Option #2: remove the skin and mix in butter to make mashed sweet potatoes. Add sweetener to taste.