01 - Rinse cranberries under cold water and discard any soft or damaged berries.
02 - In a medium saucepan, mix water, orange juice, sugar, and salt. Bring to a simmer over medium heat, stirring until sugar is fully dissolved.
03 - Add cranberries to the saucepan and cook uncovered, stirring occasionally, until berries burst and the sauce begins to thicken, about 10 to 12 minutes.
04 - Stir in orange zest and cinnamon if using. Simmer for an additional 2 to 3 minutes.
05 - Remove from heat and allow to cool to room temperature; sauce will thicken further as it cools.
06 - Transfer sauce to a serving bowl, cover, and refrigerate until ready to serve.