In “double steaming,” no liquid loss is expected. Also called double boiling, this Chinese cooking technique places food and its cooking liquid inside a covered ceramic vessel, which is then steamed in a larger pot.
Because the inner container is sealed or tightly covered, the broth is protected from evaporation and remains concentrated. The gentle, indirect heat also reduces the risk of delicate ingredients breaking apart, drying out, or becoming cloudy.
The method is associated with bird’s nest soup, shark fin soup, Chinese herbal preparations, and nourishing meat or poultry soups. It is especially useful when the cooking liquid itself is considered valuable, since flavors and soluble compounds remain in the vessel rather than escaping into the steaming water.
“Double steaming” should not be confused with ordinary steaming, where food sits directly above boiling water and some moisture can evaporate. In traditional double steaming, the intended liquid loss is effectively zero, although a poorly covered vessel or prolonged cooking can cause minor practical loss.