01 - In a medium saucepan, combine the cranberries, sugar, and water.
02 - Bring the mixture to a boil over medium-high heat, stirring occasionally to dissolve the sugar.
03 - Reduce the heat to low and simmer for 15 minutes, or until the cranberries have burst and the mixture has thickened slightly.
04 - Remove from heat. For a smooth syrup, strain through a fine mesh sieve into a bowl or jar, pressing firmly to extract as much liquid as possible. Discard the solids.
05 - Stir in the lemon juice and vanilla extract if desired.
06 - Allow the syrup to cool; it will continue to thicken as it cools. Transfer to an airtight container and store in the refrigerator for up to 2 weeks.