Galangal is a rhizome that is related to and resembles ginger, but has a mildly mustardlike, slightly medicinal taste; ginger is not an acceptable substitute. It is sold both whole fresh and as dried slices; halve the quantity when using dried. To reconstitute dried galangal, soak the slices in warm water until pliable. Galangal is also called Siamese ginger, kha in Thailand, and lengkuas or laos in Indonesia and Malaysia,