Place cranberries, sugar and vanilla in a medium saucepan. Place pan over medium heat and stir. Simmer cranberry mixture until the berries burst, about 5 to 6 minutes.
Place orange peels in a large glass container with an airtight lid, or large mason jars with lids. Pour vodka over the orange peels.
Allow the cranberry mixture to cool. Pour the cooled mixture into the glass container(s). Cover tightly and set aside for 1 week. After 1 week, strain out the cranberries sand orange peels and pour mixture into a clean bottle, using a funnel. Store vodka in the refrigerator.
To serve: Pour 2 ounces of vodka mixture over ice in a tall glass and top with tonic water. Garnish with a slice of lime.