Tsukudani is traditionally made from seaweed and possesses a potent flavour. It is usually eaten in small quantities with a bowl of boiled rice. It originates from Tsukudajima Island, Tokyo, where it was first made in the Edo era but is now eaten across Japan. The seaweed is cooked, with soy sauce used in the process along with mirin and dashi which help preserve the ingredients naturally for 2 to 3 months. Nowadays, there are many variations, which are made from small fish and shellfish.