In China, when steaming ten bamboo steamer baskets of baozi, do the top ones cook first or the bottom ones?
From a chemical engineering process perspective: isn't this just a simple sieve-tray distillation column? No condenser at the top, but a reboiler at the bottom. The closer to the column bottom (kettle), the higher the temperature, so the ones nearer the bottom cook more easily. Answer complete. Continue.