Add the pickle juice and vodka to a shaker, small cup, measuring glass, or whatever you have on hand.
Stir or gently shake.
If you would like to use the tajin garnish, dip the rims of the shot glasses in a bit of extra pickle juice and then dip it in the tajin seasoning to coat the rims.
Pour the juice and vodka mixture into the shot glasses and garnish with a pickle chip or gherkin, if desired.