声明：想照做着，一切后果自己负责。
买不到做广式月饼的 lye water，做了点小research, 发现可以自己制作替代品。
小苏打放parchment paper上250-300华氏烤一个小时。
（另外有人建议450华氏烤30分钟）
烤完后类似食用碱面，碱性更强。取3克溶于10克水即可。
强碱，小心接触，最好带手套.
用塑料或玻璃瓶装烤过的soda，密封。
不要接触金属用品。不要让小孩靠近。
原文来自以下
by Harold McGee
"Just spread a layer of soda on a foil-covered baking sheet and bake it at 250 to 300 degrees for an hour. You’ll lose about a third of the soda’s weight in water and carbon dioxide, but you gain a stronger alkali. Keep baked soda in a tightly sealed jar to prevent it from absorbing moisture from the air. And avoid touching or spilling it. It’s not lye, but it’s strong enough to irritate.
Baked soda is also strong enough to make a good lye substitute for pretzels. In order to get that distinctive flavor and deep brown color, pretzel makers briefly dunk the shaped pieces of raw dough in a lye solution before baking them. Many home recipes replace the lye with baking soda, but the results taste like breadsticks, not pretzels."
The entire article is worth reading for some good kitchen chemistry.
