In a large glass jar or container, combine the vodka, blue raspberry liqueur, simple syrup, vanilla extract, and lemon zest. Stir well to mix all the ingredients.
Add the pitted cherries to the jar, ensuring they are fully submerged in the liquid. If necessary, add more vodka to cover the cherries completely.
Seal the jar tightly and place it in the refrigerator. Let the cherries soak for at least 24 hours, but for best results, allow them to soak for 3 to 5 days.
Once the cherries have soaked, strain them from the liquid and serve them chilled as a festive treat or garnish for cocktails.