Choose - Galangal should be firm and bright looking, with a clean, relatively unblemished pale skin. ‘Lines’ dividing the surface into sections are normal, and these may be somewhat papery or peeled back. Small round ‘eyes’ on the skin are also normal. Brownish lines, spots, or small blemishes are relatively common, and should only be avoided outright when they appear very large, soft, or otherwise spoiled.

Because galangal is a root-like rhizome (much like ginger), it will generally have cut sections on its ends, and may have pink or green stems emerging from it (as in the featured image above). The cut sections will often be a bit dried out, but that's to be expected. Avoid roots with particularly wet or darkened cut sections.

Freshly cut galangal root should be white with a slight yellowy or beige tinge, and may show pink or pale brownish-yellow areas.

Frozen galangal is a good choice, and may be found in some Thai/Southeast Asian grocery stores. Galangal is also available dried/powdered, however this is not an ideal substitute for fresh galangal (see 'Culinary Info' section below for more on this subject).

Galangal can be difficult to find, and some recipes will suggest that you replace it with ginger. Despite this, galangal and ginger are NOT interchangeable in terms of flavour. The two are related and are often used together or in similar cuisines, but they do not taste particularly similar. That being said, they act in similar ways (adding a strong, pungent, somewhat medicinal character). In this sense, they are a great deal like lime and lemon: interchangeable in terms of character and use, but not in terms of flavour. Because of this, any recipe that indicates that you can substitute ginger for galangal may yield a decent end product, but not one of comparable flavour.

Frozen galangal can be substituted for fresh without any issue. Dried galangal can be used if no other option is available, but, as with powdered vs. fresh ginger, the flavour profiles are not identical.  Galangal has a very distinctive and powerful flavour, tasting somewhat like a combination of black pepper and pine needles. It has a slight sweetness, and a somewhat ‘medicinal’ quality that most find quite appealing. Fresh galangal has a sharp, very distinctive 'bite' to it. This flavour is mostly retained in frozen galangal, but disappears almost entirely in its dried form.  Aside from this, dried galangal retains the much of the flavour of fresh galangal, while also developing a musky, earthy quality.

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.

Greater galangal is a fairly uniform product (at least on a global/commercial scale). However, there are several other plants that are worth mentioning here, as they are easily mistaken for greater galangal.

Lesser galangal (Alpinia officinarum) has a flavour somewhat similar to its 'greater' cousin, and a finger-like appearance.

Kencur (Kaempferia galanga) which is sometimes (confusingly) called galangal,  has a peppery, somewhat camphorous taste.  It looks more like ginger than galangal.

Chinese keys (Boesenbergia rotunda), aka fingerroot or krachai, joins in on the confusing naming.  This skinny root is also used in Asian cooking, and is sometimes called lesser galangal.