In a bowl, combine pork mince, spring onion, garlic, ginger, soy sauce, sesame oil, rice wine vinegar, black pepper, chili flakes, and starch. Mix with a fork or chopsticks until it becomes a paste, then set aside.
Whisk together eggs, water, and potato starch until smooth.
Heat a lightly oiled ladle over medium heat. Pour in a spoonful of the egg mixture and spread it into a circle. When the bottom is set and the top is still slightly wet, add a spoonful of pork filling to the center. Fold the egg over into a half-moon shape and gently press the edges with a spatula to seal. Set aside and repeat until all the mixture is used.
In a steamer carefully add the dumplings, cover, and simmer for 8 minutes.
Make the dipping sauce. In a pan, add water, chicken stock cube, soy sauce, sesame oil, and rice wine vinegar. Stir and bring to a simmer.
Plate the dumplings, spoon over the sauce, and top with spring onion, chili, and black sesame seeds. Enjoy!