Sift flour into a mixing bowl, make a well in the centre and pour in hot water. Stir with a spatula. When the dough is cool enough to handle, knead until it is soft and pliable, dusting with flour if necessary to prevent sticking. Cover with a damp tea towel and set aside to rest for 30 minutes.
Roll out the dough into a long cylinder and divide into 24 to 25 equal portions. Roll out each piece into a thin flat disc. Place a tablespoon of filling in the centre of the skin and fold over and shape dumpling into a crescent. Cover the dumplings with a clean tea-towel.
Arrange pot stickers in a single layer on a steaming tray and steam for 6-8 minutes, then remove and set aside to cool.
Lightly grease a nonstick pan with oil and pan-fry the dumplings until browned and crisp. This takes about half a minute. Serve immediately with the dipping sauce.
To prepare the dipping sauce, combine all the ingredients in a small bowl. Mix well and adjust seasoning to taste.
To prepare the filling, combine chicken, prawns and scallops in a mixing bowl, add seasoning and mix by stirring in one direction only. Add the rest of the ingredients and adjust seasoning to taste. Leave the filling in the refrigerator to chill before use.