01 - In a medium saucepan, combine the cranberries, granulated sugar, and water. Stir to distribute the sugar evenly.
02 - Place the saucepan over medium-high heat and bring the mixture to a boil, stirring occasionally to prevent the sugar from sticking to the bottom.
03 - Reduce the heat to low and let the mixture simmer for 15 minutes, or until the cranberries have burst open and the liquid has thickened slightly.
04 - Remove the saucepan from heat. For a smooth consistency, pour the mixture through a fine mesh sieve into a bowl or jar, pressing firmly on the solids to extract as much liquid as possible. Discard the remaining solids.
05 - Stir in the lemon juice and vanilla extract, if using, until well incorporated.
06 - Allow the syrup to cool completely; it will continue to thicken as it cools. Transfer to an airtight jar or bottle and refrigerate for up to 2 weeks.