Grass Jelly is a sweet drink, popular in China and Taiwan. It is composed of sugar water and the grass jelly gelatin.
I frankly have no idea what the grass jelly actually is. On the side of the three brands of grass jelly I have in front of me, it explains in the ingredient section that grass jelly is made of: grass jelly, starch, and water. I suppose if I apply that formula recursively, then I get lots of starch and water, but that doesn't seem right. If you happen to know what grass jelly is, /msg me.
It's not too hard to make your own grass jelly drink. At a local Chinese food store, you need to pick up the grass jelly in a large 19oz can and rock sugar.
Boil about 2 litres of water, and add plenty of sugar, until it seems much too sweet. Chop up grass jelly into approximately 1 cm. by 1 cm. cubes, and throw into the boiling water. Leave overnight in your fridge to cool.
Grass Jelly is very sweet, and should not consumed in large doses. It's absolutely disgusting warm, and after too much of the stuff, almost as disgusting cold. Remember, this drink is good in moderation.
Grass Jelly drinks are also available flavoured with coconut, among other things. It's actually an improvement, I think.
Update: According to
Sylvar, and in turn according to http://vm.cfsan.fda.gov/~rdb/opa-g013.html, grass jelly is the water extract of jellywort (Mensona chinensis). See also http://waynesword.palomar.edu/ecoph37.htm. Thanks
Sylvar!