Bōdara 棒鱈 is cod that has been exposed to sun and wind over several months until it is dried to a hardness that makes like a rod of wood (bō 棒). It takes from several days to two weeks of soaking before it can be actually cooked. Although the bōdara is harvested in Hokkaido, this is a specialty of Kyoto and particularly associated with osechi cuisine of New Year.
Imobō Hiranoya Honke いもぼう平野家本家, established in the early 1700s, is well-known for its special dish, imobō 芋棒. Made from a type of taro, ebi-imo 海老芋, and bōdara 棒鱈, preparation takes two days of slow cooking. You can read more about the fascinating history and tradition of Imobō here.