PICK OVER THE CRANBERRIES and wash the orange. Zest the orange, making certain not to take in any of the bitter white pith. Juice the orange. Place the cranberries, water, orange juice and sugar in a saucepan and bring to the boil. Cook for 3-5 minutes, stirring occasionally, until the skins of the berries begin to pop. Do not overcook or the berries will be mushy. Remove from heat and stir in the orange zest. Transfer to a serving bowl and let cool. When room temperature, refrigerate for at least 2 hours before serving.