Rinse the cranberries thoroughly in a colander. Pick through them and discard any berries that are bruised or overly soft.

In a medium saucepan, combine the sugar and water (or orange juice). Stir the mixture over medium heat until the sugar dissolves completely.

Bring the sugar water to a gentle boil.

Add the rinsed cranberries to the pot. Add a pinch of salt and cinnamon if you are using it.

Return the mixture to a boil, then reduce the heat to low. Let it simmer gently for 10 to 12 minutes.

Watch for the cranberries to burst and the liquid to turn a deep red. Stir occasionally to prevent sticking.

Once most of the berries have popped and the sauce starts to thicken, remove the pan from the heat.

Stir in the fresh orange zest.

Pour the sauce into a glass bowl. Let it cool completely at room temperature. The sauce will continue to thicken significantly as it cools.

Cover and refrigerate until you are ready to serve.