Tsukudani(佃煮) is small seafood, meat or seaweed that has been simmered in soy sauce and mirin. High osmotic pressure preserves the ingredients. Its name originates from Tsukudajima, the island (in present-day Chūō, Tokyo) where it was first made in the Edo period. Many kinds of tsukudani are sold. Traditionally made tsukudani is preservable and has been favored as a storable side dish in Japanese kitchens since the Edo period.