Split the vanilla bean down the middle, length-wise, and open. (More about that here, just skip the scraping)
Combine the 1 cup water, 1 cup granulated sugar and the split vanilla bean in a small pot. Bring the mixture to a boil.
After the water comes to a boil, turn the heat to low and simmer for 10 minutes.
Remove the vanilla bean and allow the syrup to cool.
Transfer to a storage container, such as a mason jar.
This syrup keeps well in the pantry for a couple weeks, but will do even better in the refrigerator. For a thicker, sweeter syrup, use 2 cups of sugar.