I've finally figured out how to keep my savory bao buns soft and elastic and decided to try my hand with something sweet. Our local dim sum restaurant serves their pineapple bao with a crisp, flaky and crunchy topping and I have been trying to figure out how to retain the toppings crispiness. I have tried ammonium carbonate instead of a combination of baking powder and soda. Initially it’s slightly crisp but turns soggy within hours… am I missing something? (I’ve baked Lengua de Gato using ammonium carbonate and have kept the delicate cookie crisp for weeks so I know that isn’t the cause) And while I’m on this subject, how do I keep this particular bao from collapsing/deflating WITH the topping after baking?