Peel the ginger (vegetable peeler or scrape with a spoon) and then cut into thin slices.
In a medium sauce pan, combine all of the ingredients except the vanilla extract. Bring up to a boil over medium/high heat and then reduce the heat to medium low and let simmer strongly for 30 minutes.
After 30 minutes of simmering, turn off the heat and allow it to cool to room temperature. Strain the mixture through a sieve, stir in the vanilla extract, and pour into a resealable container. Store in the refrigerator for up to one month.