Infusing vodka is as easy as adding ingredients to the bottle and letting it stand. Make sure to store the vodka in a cool, dark place, such as a kitchen cabinet.
For the tangerine version:
Remove peel from tangerine in long strips using a vegetable peeler, making sure not to include any white pith. Add peel directly to bottle of vodka. For the vanilla-cardamom version: Add cardamom pods and vanilla bean directly to bottle of vodka. For the pine and juniper version: Add pine sprigs and juniper berries directly to bottle of vodka.
Let vodka stand at room temperature in a cool, dark place for 2 to 3 days, depending on desired strength of flavor. Strain; discard solids.
Strained vodkas can be stored at room temperature for up to 1 month.