Galangal (rieng) is a relative of ginger but they are quite different in terms of taste and appearance. Galangal is spicy hot, earthy, pungent with citrusy and gingery flavor. It has smoother skin than ginger and the flesh is much harder than ginger.
How to use
Galangal can be used to marinate fish or meat in some Vietnamese dishes.
Where to buy
You can buy galangal at Asian grocery stores.
Recipe that uses galangal: Vietnamese turmeric fish with noodles (Cha Ca La Vong).