Divide the dough into 18-20 equally sized pieces, then roll each into a ball. On a lightly floured surface, roll out each ball to 1mm thin.
Spoon a teaspoon of the mixture in the middle of each one, then lightly brush the edges with a little water. Fold the dough over the filling to form a dumpling, and using your fingertips pinch the edges to seal, making sure there are no gaps.
Bring a large pot of water to a boil and add the Jiaozi. Gently stir using a wooden spoon so that they don't stick together, cover with a lid and let it boil for 4 minutes. Once cooked, drain and set aside.
In a large frying pan, heat a little oil over medium heat. Fry the Jiaozi for 3-4 minutes each side or until golden. Serve immediately.