Tree ears are those mushrooms that you find in hot and sour soup. They have a very interesting texture. Kind of...um...well not to sound gross, but kind of slimy, but sort of crunchy at the same time. They are also known as wood ears. They grown on the bark of trees and look sort of kind of like ears.
The dish was tree ears in a spicy chili oil with very thin cucumber slices. They were a huge hit with us.