Make a slit down the middle of the vanilla beans, leaving the tops and bottoms. Do not remove the seeds.
Put the vanilla beans in an air-tight bottle, that will not leak if shaken, then pour in your choice of liqueur. Add enough to cover the beans.
For a period of two weeks, once a day, give the bottle a shake. Then, allow it to sit for 3 to 4 weeks, then it's done. The color will darken as the days pass.
Store in a cool location. The amount of liqueur should be 80 ml per bean.
See Recipe ID:1775232 for Classic American Vanilla Cupcakes.
Story Behind this Recipe
Since vanilla extract is expensive in Japan, I did some research on how to make it. It seemed easy, so I came up with my own recipe for an easy-to-make amount.
Feel free to use your choice of liqueur, but when using one with a high alcohol content, be careful when using it for treats for children. The ratio of liqueur to vanilla beans is an approximate. Feel free to increase the amount of vanilla beans, or mix in the seeded beans.