Eo-mandu (어만두; 魚饅頭; "fish dumpling") is a half-moon-shaped mandu (dumpling) prepared with filleted whitefish, most typically brown croakers, instead of flour dough as the wrapping. in the past, it formed part of korean royal court cuisine, and was a popular dish among the yangban (upper class). it was often served at summer birthday tables for elder family members. it is commonly eaten during buddha's birthday.

Source: Wikipedia