Gently slice open the vanilla bean skin from top to bottom, lengthwise, with a paring knife. Try not to slice the pods in half completely, just enough so you can open them up.
Scrape the vanilla beans out of the vanilla pods with the back (the blunt side) of your knife. Add the scraped vanilla beans to the glass jar by scraping your knife on the interior of the jar. Then add the vanilla pods to the jar. If necessary, trim the height of the beans with kitchen scissors to fit in your glass jar.
Cover the vanilla beans with vodka. Tightly close the lid and give the bottle a little shake.
Place in a cool, dark place such as your pantry. Let it sit for at least one and up to three months before using it, and then give it a gentle shake. The longer the vanilla sits, the stronger the flavor will be.