For best results make this simple cranberry sauce a few days in advance to let the flavours mingle. You can also add a little port, if liked.
Combine the sugar and orange juice in a large saucepan and bring to the boil.
Stir in the cranberries and clementine zest (if using), then simmer until the cranberries are tender but still holding their shape – this will take about 5 minutes if using frozen cranberries and a little longer if using fresh.
Refrigerate until needed, the sauce will thicken as it cools.
Remove from the fridge an hour before serving.
The sauce will keep in the fridge for up to one week and can be frozen if it is more convenient to make it further in advance. Defrost for 24 hours at room temperature.