Divide mixture in half and pour into large, clean mason jars. Pour vodka into the jars to cover the berries. Set aside and allow to sit for 1 week. After 1 week, strain out the cranberries and store cranberry vodka in a clean jar in the refrigerator.
To serve: Pour 2 ounces of vodka mixture over ice in a tall glass and top with tonic. Garnish with a slice of lime.