In a medium bowl, combine the lemon and orange juices with the lemongrass and set aside for 30 minutes or overnight in the refrigerator.
Add 4 cups of water, the sugar, and honey. Pour into a baking pan and freeze 1 to 2 hours.
Using a fork, loosen the lemonade from the pan and return to the freezer for 20 minutes more.
Scoop into the chilled bowl of a food processor and puree until smooth. Spoon among 4 tall glasses and serve.