Bring the water to the boil, and put in the sweet potato.
When the water returns to the boil, add the ginger, and continue cooking until the potato is tender and cooked through.
Add sugar and a little arrow starch, and allow it to dissolve completely. Then remove from the heat

Ingredients
500 g sweet potato, washed, peeled and diced
1 cup sugar
4-5 slices fresh gingerroot
4 cups water arrow starch or corn starch

Serve hot.