01 - Place the cranberries, granulated sugar, and water into a medium saucepan. Add the strip of orange peel if desired.
02 - Set the saucepan over medium heat and bring to a gentle simmer. Stir occasionally and cook for 10 to 12 minutes, until most of the cranberries have burst and the mixture has thickened.
03 - Remove the saucepan from heat. For a smooth consistency, pour the mixture through a fine mesh sieve, pressing down on the berries to extract all the liquid. Discard the solids.
04 - Stir in the vanilla extract if using. Allow the syrup to cool completely, then transfer to a sealed bottle or jar. Refrigerate for up to 2 weeks.