Chinese herbal decoctions are generally boiled and reduced, then adding a reduced amount of water and reduced again until the soup is medium coffee color, that is when one can smell the decoction, and the kitchen is filled with a very nasty smell of cooked moldy grass that makes one vomit on the spot.
A university student had to cook his herbal decoctions outdoors to avoid smelling up the dormitory room.
Traditional Chinese decoctions are always boiled in clay pots, terra cotta pots, not porcelain pots. Only clay pots are used. Chinese doctors actually do not recommend covering the clay pot with its lid while boiling the herbal decoction. Placing a lid on the clay pot while boiling the herbal decoction hastens reduction and may require the addition of more water for the secondary reduction.
A Western style pressure cooker can be used. Like placing a lid on the clay pot while boiling the decoction, the pressure cooker will hasten the reduction and will require the addition of more water for the secondary reduction. The use of a pressure cooker to boil the Chinese herbal decoction may reduce the cooking time by one half to one third.