I was invited to a party at a Chinese frien'd house he had the usual Chinese things as snacks deep fried pastry things buns and crispy fried shredded meats. But one strange thing he offered was something he called paydan these green egg looking things.
I didn't want to try them as they looked kind of gross and the host was busy so I couldn't ask him. What are paydans? They look like eggs to me.
Payday or Pidan 皮蛋 quite litterly means skin egg, or leather egg, they are as you guessed eggs I don't actually know how to make these things, the months required to make them would test my patience and the fact I am always moving around meaning they would probably be too well done. My dad used to make them though. Essentially a duck or a chicken egg is sealed up with clay ash and tea and left somewhere. This seals up the egg so it does not become rotten like normal eggs but the wihte of the egg breaks down into a jelly like substance that can be salty or once I was surprised was sweet. It is usually safe to eat, I say usually as some shysters will use dangerous chemicals to speed up the curing process, although the look of them isn't great.
It is popular in congee rice soup and actually fairly expensive compared to outer street snacks probably due to the long curing times of at least a couple of months.
If you think it is gross have a look at balut