Fire lichen

Fire lichen was a type of lichen that grew in the Underdark near sources of geothermal heat. It was recognizable by its stalks of pale orange-white. When ground to powder and fermented, it formed a paste that was very spicy but edible, added to soups and stews or spread on sporebread for flavor.

Duergar were known to ferment fire lichen into an extremely hot alcoholic beverage.