This cold noodle dish requires a bit of preparation if you make your own Sichuan shallot and garlic chilli oil. One batch will last about three months at room temperature, or longer in the fridge.

Drain all but 1 tablespoon of oil from the wok and reheat over medium-high heat. Add the Sichuan peppercorns and stir-fry for 10 seconds. Drop in the garlic,ginger, chiles, and green onions and ...