If you want to do the 100% real thing, here's the original recipe. I opted to use this one instead (no lemon grass, and using ground ginger instead of "making your own" from scratch....) - just as good and not quite as labour intensive (well, actually, at two days in the preparation, this was *the* most labour-intensive drink I've ever made!). Most of the work went into preparing the ginger-lime syrup.
Was it worth it? You betcha!