Boil the potatoes or yams until tender; drain. Peel and cut in half lengthwise. Put the butter and sugar in a heavy skillet and warmth, stirring sometimes, until melted. Add the potatoes or yams and turn until lightly browned. Add 1/4 cup water, cover, and simmer over low heat for about 10-15 minutes.

After the butter and sugar have melted, put the potatoes in a buttered baking dish, pour the butter-sugar mixture on top, cover, and bake in a preheated 350°F (180°C) oven for 45 minutes to 1 hour.