01 - Rinse cranberries, removing any soft or damaged ones.
02 - In a medium saucepan, mix water, sugar, orange juice, and zest until sugar dissolves.
03 - Bring the mixture to a boil over medium-high heat.
04 - Add cranberries, cinnamon stick if using, and a pinch of salt to the boiling liquid.
05 - Reduce heat to medium and simmer uncovered for 10 to 15 minutes, stirring occasionally until cranberries burst and sauce thickens.
06 - Remove from heat, discard cinnamon stick, and let sauce cool to room temperature. Sauce will thicken further as it cools.