Vietnamese cooking, like Chinese cooking, takes texture seriously. In fact, ingredients such as dried white tree fungus, a highly prized relative of the wood ear, lack flavor but offer interesting texture. Crunchy, resilient, and gelatinous, white tree fungus is expensive when compared with regular mushrooms and most other fungi and is thus saved for special occasions. It looks like crinkly, golden sponges and is sold in boxes or plastic bags at Chinese and Viet markets.
It is important to use a good chicken stock in this recipe. Both the mild-flavored fungus and the vegetables need the contrast of a rich backdrop. The resulting soup will remind you of an underwater scene, the florets of white tree fungus suspended like silvery blades of seaweed among the orange carrot slices and bright green snow peas. For extra flair, add hand-shredded poached chicken breast along with the carrot.