The directions for second fermenting are below and they are super easy.

Make your kefir using the basic technique, removing the grains afterwards.  Place the kefir in a clamp down jar but if you don’t have a clamp down jar, you can use a regular canning jar.  Take an organic lemon or orange and using a vegetable peeler, peel the skin of the fruit into strips. If you don’t have an organic orange or lemon, you can take off the chemicals by placing the fruit in boiling water for 30 seconds, then rinse in cold water. Place the fruit peels in the jar with your kefir and clamp the lid down. You can add a couple of orange slices, if you like. Leave the jar at room temperature for 4 to 12 hours or (up to a full day), then place the kefir in refrigerator and enjoy. If the kefir separates into whey a little this is fine and you can then place it in the fridge.

This kefir, flavored with lemon or orange, is so yummy.  It is lighter and creamier than kefir made with the basic recipe and has a little more carbonation.  The taste is worth the extra half a day and the nutrients sky rocket. You can use many different fruits (blueberries etc.) but try to keep it simple, a vanilla pod is also nice!