Doong gool le cha (Doong gool le tea) 

In a pot, add water, bring to a boil. Add doong gool le. Turn off the heat.
Leave for about 30minutes to an hour. Serve either hot or very cold.

 cool tip
It is hard to find raw doong gool le in the U.S., but if you live in a big city like LA or NY, try Korea town. Tea bags are fine but I really recommend to use the root.
One on the picture is grown doong gool le, natural doong gool le is larger in diameter
 and sliced thinly because they have strong flavor.