Combine granulated sugar and water in a small saucepan over low heat, stirring mixture until sugar dissolves. Bring to a simmer; remove from heat. (Do not boil or the cranberries may pop when added.) Stir in cranberries; pour mixture into a bowl. Cover and refrigerate 8 hours or overnight.
Drain cranberries in a colander over a bowl, reserving steeping liquid, if desired. Place superfine sugar in a shallow dish. Add the cranberries, rolling to coat with sugar. Spread sugared cranberries in a single layer on a baking sheet; let stand at room temperature 1 hour or until dry.
Note: The steeping liquid clings to the berries and helps the sugar adhere. Store in an airtight container in a cool place for up to a week.