BASICS & HOW-TO
Galangal may be quite easy to find, but this is likely to depend on the size of your city and its Asian population. While it is seldom carried in big box grocery stores, it is increasingly common in Asian grocery stores and well-stocked specialty grocers and green grocers. Fortunately, it keeps very well, and is relatively easy to keep in stock, so your chances are somewhat improved by that fact.
Large quantities of galangal (1-2 lbs) can be purchased online (depending on where you live and any shipping restrictions), so if you can’t find any local to you, you could consider purchasing a large batch and sharing it (or making and freezing large quantities of Thai curry).
Galangal is in season year-round.
Fresh galangal has a sharp, distinctive ‘bite’ that disappears in the dried product. Dried galangal loses this biting character and gains a musky, earthiness while retaining much of the overall flavour of its fresh counterpart. Fresh frozen galangal loses a little sharpness, but is otherwise a great substitute for fresh.
Fresh or frozen galangal is generally best to use, especially in curry pastes. That being said, dried galangal can work very nicely in intensely spiced dishes and in long-cooked soups where the sharp taste of the fresh rhizome would be lost or unappreciated.