Select a pint jar with a tight fitting lid (canning jars work great).
Bruise or chop the mint leaves to extract the oil. You can do this by gently crushing them between your fingers or mashing with the bottom of a cup, or simply chopping them with a knife. Place the leaves into the jar.
Pour the vodka over the leaves and give the jar a gentle swirl. You will notice the leaves floating at first; they will sink eventually.
Store in a cool, dry, dark place (such as a cupboard) and swirl once a day for at least 4 weeks (or longer, if you prefer a stronger extract).
Strain out the leaves and pour the extract into a dark jar or other container (exposing your extract to light can decrease shelf life). Will keep for up to 6 months.
Recipe by Yellow Birch Hobby Farm at https://www.yellowbirchhobbyfarm.com/homemade-mint-extract/