Drain the tofu of excess water very well. (The photo shows the tofu wrapped tightly in kitchen paper towels.)
Put the ground chicken, mashed tofu and the flavoring ingredients - chopped leek, soy sauce, sesame oil, grated ginger, katakuriko and salt - in a bowl, and knead together with your hands well until it starts to turn white-ish.
Drop spoonfuls of the mixture into boiling hot soup or into a hot pot. Simmer the dumplings for 3 to 4 minutes and they're done.
Story Behind this Recipe
I experimented a lot before getting to this version of chicken dumplings. By using tofu instead of eggs they become very light and fluffy. I left out sake since the dumplings can sometimes contain too much alcoholic depending on the temperature they are cooked at, and instead of using pepper I used ginger to for added flavor.
I recommend using a mixture of 100 g of ground white or breast chicken meat and 100 g of dark or thigh meat. Combine the dumpling mixture very very well.