There are several ways to cook mandu, which was once part of the royal cuisine. It was said to have found its way in Korea through the Mongolians which brought with them new ways of food consumption. But mandu is etymologically tied to Central Asian names for the same type of food, which lends credence to the argument that it might have found its way to Korea from the Middle East via Silk Road.
Regardless, mandu as a Korean food is a favorite among the crowd. You can fry it, steam it or boil it – according to how you like it. The traditionally, it is primarily filled with equal parts ground pork and ground beef, but mixed in with buchu (Asian chives), shiitake mushrooms, onion and tofu. The egg here would serve as your patty binder, but you can do away with it if you think your filling is solid enough to hold through a cooking process.
While this seems easy to make, the skins are actually very delicate and improper handling would result to a botched mandu work. Just imagine accidentally punching a hole through the mandu skins – your filling would end up all over the place! There’s an additional pressure here since tofu is filled with water so it is important to drain it and pat it dry.
*photo source: https://blog.naver.com/pointreal/220227953237
Another delicious Korean dish: https://thisiskoreatours.com/drooling-over-bulgogi/