In a mixing bowl, add water to the flour gradually. Mix with chopsticks/spatula until no more loose flour can be seen. Combine and knead into a dough.
Leave to rest (covered) for 10-15 minutes then knead again until smooth (see note 3).
Cover and rest for a further 30-60 minutes until it becomes soft.
Prepare the filling
Put tofu, Chinese chive, mushroom and carrot into a large bowl. Place scallions, ginger and ground Sichuan pepper on top.
Heat the oil until smoke appears. Pour it over scallions, ginger and Sichuan pepper.
Add light soy sauce, sesame oil and salt. Mix well.
Roll the wrappers
Divide the dough into three parts.
Roll one part into a rope then cut into 10 equal sections (cover the rest to prevent them from drying out).
Press each piece into a small disc with the palm of your hand.
Use a rolling pin to flatten it into a thin disc. Dust with flour if it sticks.
Assemble the dumplings
Place a spoonful of filling on the wrapper.
Fold and seal the middle part.
Make 2-4 pleats from each end.
Press all around the edge to seal completely.
Fry the dumplings
Coat a frying pan with a thin layer of oil. Heat up over high heat. Place the dumplings in the pan.
When the bottom part becomes golden brown, pour in water (enough to cover ⅓ of the dumplings) then cover with a lid.
Uncover when the water evaporates completely. Cook another 30 seconds to crisp up.
Prepare the sauce
Heat the oil until smoke appears. Put chilli flakes, ground Sichuan pepper, scallion and sugar into a bowl. Pour hot oil over.
Add light soy sauce, black rice vinegar. Mix well.
Make-ahead tips
Right after the dumplings are assembled, lay them on a tray to freeze (dust with flour or line with parchment paper). Then put them in an air-tight bag when frozen.
Whenever you need to cook them, pan fry the usual way without defrosting.
Video
Notes
Please be aware that measuring flour by cups is less accurate and the flour-water ratio may vary depending on the brand of your flour.
Soak dried shiitake mushrooms in cold water for at least 8 hours. You can use fresh ones too.
You may use a stand mixer with a dough hook to do step 1 & 2 all at once.