Tiedan is a famous snack in Tamsui Town, Taipei County, Taiwan. According to legend, the man who ran a small noodle stall on the ferry bow was nicknamed the "Haijiao Grand Hotel" by the sea-seeking people (Haijiao). Huang Zhangzi, on a rainy day, because business was not good, he kept returning the braised eggs to the pot. Because the sea breeze kept blowing, the braised eggs became smaller and darker. Unexpectedly, the customers liked this kind of eggs. The chewier and more delicious black braised eggs were later interviewed by Minsheng Daily reporter Lin Mingyu in 1983, and he wrote a report titled "Grandma's iron eggs, she insists on getting them." The report attracted the attention of many people, including The media even came from as far away as Japan to cover it. After that, the iron egg became a famous snack in Tamsui. After Huang Zhangzai (Grandma) became famous for her Grandma's Iron Eggs, she mass-produced iron eggs for merchants to sell. Yang Biyun was one of the wholesalers at that time. Later, she introduced the production technology herself and was the first to sell "Grandma's Iron Eggs" After applying for a registered trademark, it later became the ancestral store of Tiedan, and is now the famous "Grandma Tiedan" on the old street. Grandma's daughter Huang Linghong, although she has been helping her mother in the shop to make iron eggs since she was eight years old, and the iron eggs she makes have the "taste of grandma", she thinks it was because she did not understand how to register a trademark. I let others apply first, and only applied for a registered trademark of "Seaside Iron Egg". Huang Linghong said helplessly that even though the local town office knew about this history, they always tried to invite Huang Zhangzi’s own "seaside iron eggs" to participate in various garden fairs to promote them, but often the guests would always say that they were not grandma’s iron eggs. I didn't want to buy it, but missed the taste of real grandma's iron eggs. Despite this, in order to commemorate the founder of the iron egg, Grandma, Huang Linghong later added the word "grandma" to the registered trademark, so the trademark became "Seaside Grandma Iron Egg". "Grandma's Iron Egg" has long been famous, but there is no place for "Seaside Grandma's Iron Egg" in the iron egg market, so Grandma's Iron Egg has declined. Another theory is that Ms. Yang Biyun, who ran a breakfast shop and also sold braised eggs, once accidentally marinated the eggs for too long, and the eggs became harder and darker. The black and hard braised eggs tasted very delicious. After that, Ms. Yang called the eggs "iron eggs". Yang Biyun originally wanted to name this delicacy "Yuanzu Iron Egg", but there is a chain store "Yuanzu Food" that specializes in selling mochi. In order not to infringe the patent rights with the same name as Yuanzu, Yang Biyun named this iron egg. It's called "grandma's iron egg". The production of iron eggs is very time-consuming. Every day, the marinade containing soy sauce and five spices must be used. After three hours of marinating, the iron eggs must be dried with a fan. This process must be followed every day. It takes one week to complete the iron eggs.