Add flour, water, oil sugar, yeast to a big bowl, make a dough, add the water slowly when stirring the flour
Let the dough rest for 20 mintes with a cover or plastic wrap
Add 2 tablespoon oil to a wok, heat over high medium heat, add dried preserved mustard after soaking, stir-frying for 3- 5 minutes, turn off the fire.
Add stir-fried preseved mustard, 2 tablespoon light soy sauce, 1 teaspoon cooking wine, 1/4 teaspoon salt, 2 tablespoon oil to a big bowl, mixed well
Make the dough into cylinder, then cut into sections, make every section into the wrapper with rolling pin,
Add right amount fillling on the every wrapper, take the edge with your hands, close it up, squish it, and make a thin cake with rolling pin.
Pan frying them until cooked through.