01 - In a medium saucepan, combine the cranberries, granulated sugar, and water. Stir to distribute the sugar evenly.
02 - Set the saucepan over medium-high heat and bring the mixture to a rolling boil, stirring occasionally to prevent the sugar from sticking to the bottom.
03 - Reduce the heat to low and let the mixture simmer gently for 15 minutes, or until the cranberries have burst open and the liquid has thickened slightly.
04 - Remove the saucepan from the heat. For a smooth, refined syrup, pour the mixture through a fine mesh sieve into a bowl or jar, pressing firmly on the solids with the back of a spoon to extract maximum liquid. Discard the spent cranberry solids.
05 - Stir in the lemon juice and vanilla extract, if using, to brighten and deepen the flavor profile.
06 - Allow the syrup to cool completely at room temperature; it will continue to thicken as it cools. Transfer to an airtight jar or bottle and refrigerate for up to 2 weeks.