This is a great question. I did a bit of searching and found some suggestions. I've not tried any of them, I'd be interested to hear what your opinion of them is.

1. Make an infusion with the leaves. It is lemony with a hint of ginger. Add the leaves to hot or cold water. If made hot I guess a spot of honey might help too.
2. Use the fresh leaves to line bamboo steamers when cooking fish, vegetables, and dumplings.
3. Add a few leaves to soups, stews and curries.
4. Air dry the leaves (hang in an airing cupboard) and use as fresh. You'll need more leaves than fresh.

As far as harvesting is concerned, just cut away the stalks as you need them, leaving the rest undisturbed. Cut a stalk once it is around about 2 1/2" to 3" long and 3/4" wide at the base. In hot climates it grows quite vigourously. The colder your area is the slower it is likely to grow. If you want to get a larger crop, you can divide the bulbs and plant them out once established.