Unadon (鰻丼, an abbreviation for unagi donburi, "eel bowl") is a dish originating in japan. it consists of a donburi type large bowl filled with steamed white rice, and topped with fillets of eel (unagi) grilled in a style known as kabayaki, similar to teriyaki. the fillets are glazed with a sweetened soy-based sauce, called tare and caramelized, preferably over charcoal fire. the fillets are not flayed, and the grayish skin side is placed faced down. sufficient tare sauce is poured over so that some of it seeps through the rice underneath. by convention, pulverized dried berries of sanshō (called japanese pepper, although botanically unrelated) are sprinkled on top as seasoning.

Source: Wikipedia