Seeing the discussions about lye water, I thought I can make some clarifications. Lye water is an authentic ingredient in traditional noodle making. Chinese noodles put a lot of emphasis on how “tough” the noodles were and the more “tough” or elastic the noodle is, the better is the noodle considered to be.

Lye water is used for helping gluten development in the noodle making process. Thus, the more lye water you add, the tougher you will have to knead the dough. The action the lye water does is increasing the pH so that more gluten can form. Such is done to increase the “toughness” of the noodles, which is “desirable” depending to your taste. Chinese chefs often say “Alkaline is the bone of the noodle, while salt is the tendons” – the two gives the noodle its unique texture and their respective amounts has a great impact on the texture of the noodles produced.

(@Janet it is definitely the wrong way to put the dough in alkaline, baking soda definitely can be a substitute. What traditional Chinese uses is some kind of ash from the remnants of burning certain herbs -> add water = alkaline solution/kansui/lye water)

Most Chinese recipes also use high-gluten flour in noodle making for the same reason (Usually, it’s about half high gluten flour and half all purpose flour). Typically, the flour mixture used for Chinese noodles has a protein content of approximately 10.5-12%.