If making your own noodles make sure the dough is fully prepared before beginning the lamb stir fry. Set a pot of water to boil so that it will be ready to boil the noodles as soon as the lamb is done.
Add the cumin, Sichuan peppercorns, and coriander to a dry pan and heat over medium-low heat. Stir and toss frequently. Toast until the spices are fragrant and beginning to pop, about 5 minutes. Take the spices off the heat and grind until partially powdered. You can use a mortar & pestle, a spice grinder, a coffee grinder, or by crushing the spices with the bottom of a heavy pan.
Combine the lamb, Shaoxing wine, salt, oil, and 2 teaspoons of the ground spices and mix. Add the cornstarch and mix by hand until the lamb is fully coated. Marinate for 15 minutes.
Cook lamb sauce
Add the oil to a large skillet and heat over high heat until the oil begins to smoke. Add the marinated lamb and spread it into a single layer. Separate the individual slices with minimal overlapping using a pair of tongs or chopsticks. Add the garlic and ginger on top. Leave the lamb to sear for 30 seconds to a minute until the bottom is browned.
Once the lamb is browned on one side, stir occasionally until the lamb is mostly browned on both sides and the aromatics begin to turn golden. It’s OK if the inside of the lamb is still slightly pink.
Add the red onion and green chilis. Stir fry for 10 to 20 seconds.
Add the spice mix and toss to coat everything with the spices.
Pour in the sauce and scrape the bottom of the pan to lift any caramelization. Stir fry for another 30 seconds.
Turn the heat off and add the cilantro, stirring to incorporate. Transfer everything to a big plate so the lamb stops cooking.
If using hand-pulled noodles - Take your prepared dough, stretch each piece, and add it to the boiled water. Cook them for 1 to 2 minutes.
If using packaged noodles - cook them according to the instructions.
Transfer the cooked noodles into 4 bowls.
Add the lamb and sauce over the noodles. You can add extra chili oil, chinkiang vinegar, and soy sauce to taste. Enjoy!
You will need about 2/3 batch of the hand-pulled noodles for this dish if you like an intensive result (like the restaurant version). But I recommend making the whole batch so you will be sure to have enough noodles, and maybe some leftovers.
You can use pre-ground spices but you may want to increase the amount by 1 teaspoon each as they will be less fragrant. If you do, skip step 2 and when you add the spices in step 6, stir fry for 10-30 seconds, until the spices are fragrant, before adding the sauce.
If 1/2 cup chili oil sounds like too much to you, use 1/4 cup in the cooking and add more later if needed.