The purpose of steeping or decocting raw Chinese herbs in a formula is to draw out the therapeutic constituents of the herbs in to the water.
The recommended container is ceramic or glass, and it is important that it has a lid. You should avoid metal or cast iron teapots as Chinese herbs can react with the metals altering their therapeutic properties, or worse, have negative effects. If you must use a metal container, use stainless steel.
Room temperature spring water or purified water are the best choices for cooking herbs.
The water should cover the herbs by about 2 inches and they should be soaked for at least an hour before turning the heat on. Bring the water to a rolling boil, then turn the heat down to a low simmer. Depending on the kinds of herbs, there is a great deal of variation in the cooking time. The average time is about 20 to 30 minutes.
Do not lift the lid of the teapot when cooking as the volatile oils can evaporate and escape.
Once you've made the first cup of tea, the same herbs are usually cooked a second or even third time. The first cooking is said to effect the patient on more of the Qi or more superficial level as the temperature energetics of the herbs are released. On the second or even third steeping, more of the taste energetics are said to be released, which effects the patient on more of the blood or internal level. For this reason, it is good to mix the batches of tea if possible.
Once cooked, strain the herbal concoction through cheesecloth, a metal strainer, or with the lid of the teapot.
The taste of Chinese herbal teas can be quite unpleasant to some people, but with time the patient will usually build an affinity for the formula they are drinking, especially if is well suited for them. If necessary, the tea can be watered down and consumed in a few cups versus just one. Honey can also be added to sweeten the formula, but do this only with the consent of your Chinese doctor, as it can change the properties of the formula.
Some herbs are cooked separately
Rare or expensive herbs such as Ginseng should be sliced and decocted separately for 2 to 3 hours to extract the maximum benefit from the herb and avoid interaction and absorption from other herbs. This will also prevent overcooking the other herbs in the formula.
Some herbs come wrapped in cloth or as packets
Very small substances such as powders, seeds, and some flowers should be wrapped in cheesecloth or a small bag so they can be decocted with the rest of the formula without creating turbidity or discomfort when drinking the tea. A good example of this would be Xuan Fu Hua.
Some herbs are melted
Gelatinous or viscous herbs such as E Jiao or Yi Yang should be heated gently to melt them slowly and to not char the substance.
Aromatic or fragrant herbs are added last
Herbs with volatile herbs such as Bo He should be added to the decoction approximately 3 to 5 minutes before the cooking process is completed.
Herbal formulas are best taken 1 to 2 hours before eating to allow for maximun digestion and absorbtion of the herbs.