1. Take a paring knife or other knife with a pointed tip and, beginning about a half inch from one end, split each bean down the middle lengthwise.
2. Pour vodka into glass container. Submerge vanilla beans completely in the vodka. Cover tightly with lid. With a marking pen, write the date on the bottom of the jar or bottle.
3. Place in a cool, dark place for 4 to 6 weeks or longer. Shake once a day during the first week, then once or twice a week thereafter. The clear vodka will gradually turn a deep brown.