Wash mandarins and cut them into thin rings. Put them in a non-metallic bowl and pour vodka, add vanilla and close the container. Leave to stand overnight. Boil the syrup of 250 ml water, sugar and lemon juice. Mandarins them good strain through cheesecloth and mix with the cooled syrup. Spill in bottles. Once a month is overflowing. Store in a cool dark place.