Recipe:

1. Put the flour in a bowl and add the water. Gently mix with a pair of chopsticks or a fork, until all the flour is mixed in, then knead with your hand. Cover and leave to rest for 30 minutes. 
2. Cook the chopped potatoes in a pan of salted boiling water for 10 minutes, or until tender then mash the potatoes with a fork. Heat up a little oil in a large frying pan, and saute the onion for 3-5 minutes until soft. Add the garlic, ginger and mushrooms and saute for 5 more minutes. Add the cabbage and let cook for another minute. Remove from heat and mix in the potatoes, sesame oil and soy sauce. Leave to one side.
3. Cut the dough into four and shape each one into a log. Cut each log into 7 pieces, then roll each into little balls. Roll out each ball into thin, flat circles. Keep them separated with small pieces of parchment paper.
4. When you're ready to make the dumplings, add 1 tablespoon of filling to the middle of a wrapper. Fold half of the wrapper over the filling and pleat the edges with your fingers to seal. Repeat with until you've filled all the wrappers.
5. In a small bowl, stir together all the dipping sauce ingredients.
6. Heat a little oil over medium-high heat in a frying pan, and add a few potstickers, cooking them in batches. Once the bottoms of the potstickers start to brown, add a splash of water and cover with a lid. Steam for 3 minutes, until the potstickers are cooked and the water has evaporated. Remove the lid and cook a little longer to make them crispy. Transfer to a towel-lined plate to remove any excess oil. Serve hot with the dipping sauce.