Stock is the foundation of all good cooking. I emphasize this because it is so important a principle. Good stock, especially chicken stock, is necessary for the cuisine of Hong Kong, whose subtle flavors, fresh ingredients, and fast cook cooking techniques require very good stock. Light, flavorful, and versatile chicken stock should be considered a staple, to set beside salt, cooking oil, or soy sauce.

There are commercially prepared canned or cube stocks but many of them are of inferior quality, being either too salty or containing additives and colorings that adverse affect your health as well as the natural taste of good foods. Make your own, it is the best. You can make a big batch and freeze it for your own use when needed. In making a good stock, here are a few rules to remember:

* It is best to use about 50 percent bones and 50 percent meat. Without meat, the stock will not have the necessary body or richness or depth of flavor and will taste watery. Stewing old hens is best if you can find them, because they are inexpensive and full of flavor.

* Stock should simmer. Never let the stock come to a boil because that will result in a cloudy and heavy stock. Flavors and digest- ibility come with a clear stock.

* Use a tall heavy pot so the liquid covers all the solids and evaporation is slow.

* Simmer on low heat and gently skim the stock every now and then to remove any impurities.

* Strain the stock slowly through several layers of cheese cloth or a fine mesh strainer.

* Allow the stock to cool thoroughly before storing in the re- frigerator or freezer.

If you make a habit of saving your uncooked chicken bones and carcasses, you will have the essential ingredients for stock in no time. It makes good economical sense also.

The stock should be rich and full-bodied, which is why it needs to be simmered for such a long time. This way the stock (and any soup you make with it) will have plenty of taste. With a good, stock, you will also get good sauces for a true taste of Hong Kong!

Cut up the chicken and put the pieces and parts together into a very large pot. Cover them with the cold water and bring the stock to a simmer. Using a large, flat spoon, gently skim off the scum as it rises from the bones. Watch the heat as the stock should never, boil. Keep skimming until the stock looks clear. This can take from 30 to 40 minutes. Do not stir or disturb the stock.

Turn the heat down to a low simmer and add the ginger, scallions, and salt. Simmer the stock on a very low heat for at least 3 hours, skimming any fat off the top at least twice during this time. Strain the stock through several layers of dampened cheesecloth or through a very fine mesh strainer, and then let it cool thoroughly. Remove any fat that has risen to the top. It is now ready to be used or transferred to containers and frozen for future use.

Makes 6 quarts.

From "Fragrant Harbor Taste", Ken Hom, 1989 Fireside (Simon and Schuster), New York. Isbn 0-671-75444-0.