'Steaming in closed vessels', or clear-simmering can be achieved by very slow cooking in a casserole or heavy pot placed over the lowest heat, with an asbestos sheet inserted under the pot, or alternatively by placing the casserole or pot in an oven at around 150 °C.
"Steaming in closed vessels", or clear-simmering (清炖, Qing Dun) can be achieved by very slow cooking in a casserole or heavy pot placed over the lowest heat, with an asbestos sheet inserted under the pot, or alternatively by placing the casserole or pot in an oven at 150 °C ( 300°F ). In China , clear-simmering is practiced when cooking in earthenware casseroles (砂锅, glazed on the inside ) on top of a small charcoal fire. When the smoldering or half-burning charcoal is partly buried in its own ashes the heat can be maintained at a very slow simmer, with the result that the materials and ingredients are cooked in a completely undisturbed state. The pieces of food become very tender and the resulting soup or broth is crystal clear - a very good accompaniment to rice and other bulk foods. Foods so cooked are particularly suitable for elderly people who are unable to chew and grind effectively with their teeth, and yet they are also the very people who appreciate flavorsome food and variety of ingredients. With an eye to health-cooking, a percentage of "quick-to-cook" ingredients may be added to the simmering soup or stock to cook for just 10-12 minutes, so that when the dish is served it will provide the richness and flavor of the long-cooked materials as well as the sweet-freshness of the short-cooked ingredients.
Clear-simmering can also be done by cooking in a closed receptacle placed in a steamer, which has the same effect as cooking in a double-boiler in the West, which is to ensure that the temperature of the food being cooked will reach no higher than boiling point.
Clear-simmering differs from red-cooking 红烧 in several ways. It is clear because no soy sauce is used. Secondly, it is less dry and the slow cooking yields clear soup to serve as drink at the table. Except a few developed dried vegetables such as dried winter mushrooms, most clear-simmered dishes are meat and fish dishes. As soon as boiling starts, very low fire should be used. Any continued quick boiling will make the soup muddy and uninviting. Good Chinese cooks are proud of good clear-simmering, but ordinary cooks hesitate to clear-simmer, since it demands too much quantity, quality, and time. A practical advantage about a clear-simmered dish is that it combines the part of a main dish and that of a soup.