Crush the black peppercorns with a mortar and pestle until they have the same consistency as coarse ground coffee.
Pour the crushed peppercorns into a clean 750 mL bottle. Add the vodka to the bottle. Shake vigorously for 15 to 20 seconds.
Label the bottle to identify the contents and the date it was made.
Store the vodka in a cool, dark place for two to three weeks, shaking daily to re-combine the ingredients.
Strain the black peppercorns out of the vodka through a coffee filter, catching the vodka in the second clean 750 mL bottle.