Use a sharp knife to slice down the length of each vanilla bean, leaving the ends intact.
Place the beans into a jar and pour the alcohol over the beans, ensuring they are fully covered. This is important as uncovered beans may go slimy and ruin your extract.
Screw the lid onto the jar, and use a piece of tape to mark the date. Place the jar into a cupboard or other dark cool place that you won't forget about. Every once in a while, give it a shake.
After two months (min, not max) remove the beans and decant the vanilla extract into small bottles.
Nutrition values are an estimate only.
Does it matter what kind of alcohol I use? Keep in mind that the alcohol use will impart some flavour on the final product, so you have to be ok with that. Vodka is nice and neutral. Rum and bourbon will both lend a bit of flavour.
How long do you have to wait for the vanilla extract to be done? The recommended minimum is two months, but I often go much longer. I prefer 6 - 18 months if possible.