Meat or poultry stock needs long, slow cooking in order to extract as much flavor as possible from the bones. But vegetable stocks can be made quickly or slowly and fish stocks are always made quickly. Cooked bones can be used for stock and do not need blanching, but will have lost some of their flavor and are not as good as raw bones. For poultry or game stock, use the carcass from a roasted bird. Avoid using lamb bones, which give an unpleasant flavor.
It is often better to place raw bones in a pan of cold water, bring them to the boil, then drain and refresh before using them to make stock. This will remove impurities that would give the stock a tainted taste and unpleasant grey color.
Do not boil stock during the cooking process as this will make it cloudy. But after the bones and vegetables have been strained off, the stock may be returned to the pan and boiled to reduce it. Raw beef bones can be used for an all-purpose meat stock.
** Asian Recipes