Li Duanduan makes this recipe with "seasoned chicken paste" a finely chopped mixture of chicken and shitake mushrooms available at Chinese butcher shops, but ground chicken makes and excellent substitute. If you can't find dried shitake mushrooms (or don't have time to re-hydrate them overnight) you can use fresh for a similar flavor.
dried shiitake mushrooms
packages round dumpling wrappers
Chinkiang vinegar or rice vinegar
Re-hydrate shitake mushrooms: place dried mushrooms in a bowl, pour hot water over them to cover, and weigh them down with a saucer or jar to ensure they stay submerged. Leave overnight.
Drain mushrooms and squeeze them to remove excess water. Finely chop mushrooms, scallions, and jicama.
Mix vegetables into the chicken, then add the olive oil, soy sauce, sugar, and salt and mix to combine well.
Test the mixture: Boil a small amount of water in a saucepan and use a spoon to scoop out about a teaspoon's worth of the chicken mixture. Place the spoon with mixture into the water and boil for 2-3 minutes, until it is cooked through. Taste, and adjust seasonings if needed.
Set up your workspace with a small bowl of water, a tray or sheet pan covered in a kitchen towel, and plenty of paper towels. Fill each dumpling according to the step-by-step instructions here [this should be a link], or by simply wetting the edges of the wrapper with water and folding the wrapper in half with some of the filling inside to create a half-circle, pinching the edges firmly to seal. When making dumplings, begin with a small amount of filling, so that they're easier to work with, and increase the amount as you get used to the technique. Set each dumpling aside on the cloth-covered tray.
To cook the dumplings, bring a large pot of water to a boil and drop a few dumplings into the water. When the dumplings float to the surface, add a cup of cold water to the pot. When the water reaches a boil for a second time, the dumplings should be done.
Serve with bowls of Chingkiang vinegar or with a mixture of equal parts rice vinegar and soy sauce and a few drops of sesame oil.