IN CHINA, when a housewife cooks dinner, she doesn't look at a cookbook and make a grocery list. Instead, she buys what is available at the price she cay pay, and she looks for what is ripe in her garden. To this she adds soy and seasonings and the centuries-old knowledge of what goes well together. I like to call this improvisational cooking. It exists in every cuisine and is the root from which that cuisine grew. In this kind of cooking recipes are used, but they are intuitive; measuring is done with the hand and eye and not the cup and spoon.

Stir-frying seems the perfect vehicle for improvising. You can taste the results immediately. You can't go too far wrong with crisp vegetables and thin strips of meat. And if it isn't right, the cost wasn't enormous in either ingredients or time.

But to do this cooking well, you need a set of rules, a Chinese seasoning shelf and a little confidence. If you were Chinese you would have learned the rules by osmosis at your mother's table. Your tastebuds would know what to put together. For those who didn't learn Chinese cooking at home, here are a few rules that will help.

1. Cut the meat in cubes, thin strips or wide strips. This is determined by the meat itself (if you are using a thin cut of beef or pork you will not be able to cut it in cubes) and by the vegatables you are using in the dish. (It is difficult to julienne a lima bean.) In Chinese cooking the meat and vegetables are, whenever possible, cut in the same shape and size. This makes it much easier to eat with chopsticks and is part of the harmony of the dish.

2. Marinate the meat. Chinese marinades are always simple. Their purpose is to give a protective coating to the meat to preserve the flavor and juices. There are four general types of marinades: cornstarch with soy, wine and seasonings, egg yolk with seasonings and whole egg with cornstarch and seasonings. It is not necessary to let the meat marinade for a specific period of time. By the time you chop the vegetables, make the sauce mixture and heat the wok, the meat will be ready to cook. In Chinese cooking the meat, fish and seafood are always marinated. Recipes for marinades are below.

3. Cut the vegetables in the same shape as the meat, and try for the same size. This is not always practical. Remember that cutting vegetables all the same size and thickness will make it possible to cook all to the same crisp texture. Place your vegetables in separate piles on a large plate.

Mix the sauce in a small bowl. Cinese sauces are simple mixtures of flavorful and aromatic ingredients used to season the dish. Generally the volume of sauce is very small. Just a thin glaze on the meat and vegetables. There is only one province that uses a lot of soupy sauces in its cooking, Fukien, and it is not well-known for its cuisine. To help you with your improvisation, below are some basic sauce recipes.

5. Place the empty wok over the highest heat possible on your stove. If you are using an electric stove, try to find a flat-bottomed wok. Do not use a ring. This keeps the wok too far away from the heat. Chinese cooking is done at temperatures in excess of 600 degrees. To attain this without burning the oil, you heat the wok first, then add the oil. Give the oil about 5 seconds to heat up, then add a portion of the meat. Toss and stir the meat until it is cooked. Remove to a plate. Add the remainder of the meat in small portions to cook very quickly. Add more oil as needed.

6. Clean the wok if necessary. Reheat. Add a splash of oil. Begin cooking the vegetables, starting with the one that takes the most cooking time, and working down to the ones that take the least or are precooked (water chestnuts, bamboo shoots, etc.) Generally ginger goes in first. Broccoli, asparagus, cauliflower, green beans, snow peas and other fibrous vegetables need to be stir-fried until you note a brighter green color, and then steamed for 3 minutes with either the steaming sauce of 3 tablespoons of plain water. Place a tight lid on the wok during steaming. Green peppers need only a short stir-frying, and green onions need almost none.

7. Return the meat or seafood to the wok and reheat it.

8. Stir the sauce mixture well. This is very important. Many of the sauce ingredients will settle to the bottom of the bowl. Add the sauce to the wok and quickly stir-fry. When the sauce is clear and well-distributed, poor onto a platter and serve.

Every cuisine has flavors and seasonings combinations that are identifying signals. When you walk into an Italian restaurant you expect the smell of tomato, garlic, oregano and olive oil. It identifies the cuisine for you. In the Chinese cuisine these identifying ingredients are soy, sesame oil, ginger, garlic and rice wine. To make your stir-fried dishes taste Chinese, you must have these and other ingredients on your shelf:

Soy sauce -- Buy Kikkoman or an imported Chinese brand of soy. Americanized soy is not acceptable for Chinese cooking. You will find that Chinese soy comes on thick, thin or medium and light or dark. Thin (or light) is for table use, medium is for cooking, and thick (or dark) is for specialized stewing. Your best buy is medium. Kikkoman is a medium soy sauce.

Rice wine -- The Chinese shao hsing wine is available in large cities but may be difficult to find. You may substitute a dry Japanese sake or dry cocktail sherry.

Rice vinegar -- Japanese rice vinegar is more commonly available. There is quite a difference in taste and acidity between rice vinegar and wine or cider vinegar. You may decide that you like it on salads, so give it a try.

Fresh ginger -- There is no substitute for fresh ginger. Nothing else can give you the aromatic perfume or the spicy tang. Ginger seems to be available in the produce sections of most large grocery stores. If you live in an area where it is difficult to obtain, then buy in large quantities and freeze it or preserve it in wine. To freeze, cut in short sections and leave the skin on. To use, thaw under hot water and cut off what you need. Refreeze the remainder. To preserve in wine, peel the ginger, place in a jar. Fill the jar with rice wine or sherry. Frozen ginger does lose its crisp texture, but the flavor is good.Ginger preserved in wine will keep the texture but will take on some of the wine flavor.

Sesame oil -- This aromatic oil is made by pressing toasted sesame seeds. It is a golden amber color with a strong aroma. Sesame oil is used in small amounts, as a seasoning, and is rarely used as a frying oil. Be certain that you buy an Oriental imported brand. Health food stores sell sesame oil made from untoasted seeds that lacks the necessary flavor for Chinese cooking.

Oyster sauce -- The liquor from oysters, soy sauce and caramel are combined to make this unusual sauce. It doesn't really have much oyster flavor. However, it adds a rich taste to beef and chicken and goes well with many fish and seafood dishes. It is available in most gourmet grocery stores. It is possible to make your own oyster sauce, but I don't recommend it. It is best to refrigerate it after opening.

Szechuan peppercorns -- These dried seed pods are more herbal in flavor than spicy. Crush them with the handle of your cleaver or grind in a pepper grinder.

Five-spice power -- Szechuan peppercorns, star anise, fennel seeds, Chinese cinnamon and cloves make up this powerful spice. Used to season duck and fish, it comes prepackaged in Chinese markets.

Sugar -- The Chinese use sugar in the same way that we use salt. It has the ability to excite the tastebuds so that they become aware of other flavors. It is used in teaspoon and half-teaspoon amounts in most sauce mixtures.

Cornstarch -- Buy a box of cornstarch just for your Chinese shelf. It is used in marinades and to thicken sauces. The ancient Chinese used another starch, lotus root power, for the same purpose. It is not easily available, so carnstarch takes its place.

Now, just how to you improvise? Take a look in your refrigerator. What kinds of meat, fish, poultry or seafood do you find? Chinese cooking is done with small amounts of meat or fish, but it must be raw. What about vegetables? Almost any fresh vegetable is a possibility. Green onion and carrot are often used for color as well as flavor. Green peppers seem a natural to this cuisine. Now choose a marinade that suits the meat you are cooking and a sauce that will complement both the meat and vegetables you are cooking together. Do you love garlic? Mince it and add it to the oil before you stir-fry the meat. Like a strong flavor? Mince some ginger and add it to the garlic. Do your thing; but believe me, you can be certain that sometime during the last 5,000 years a Chinese housewife has done it before you. MARINADES

Here are the basic marinades. To them you might add seasonings such as grated ginger, ground szechuan pepper, crushed garlic, rice vinegar, five-spice powder, sesame oil, sugar, salt or oyster sauce.

For anything stir-fried -- Mix 1 tablespoon soy sauce, 1 teaspoon rice wine and 1 teaspoon cornstarch.

For chicken and other poultry -- Mix 1 egg yolk, 1 tablespoon soy sauce, 1 teaspoon rice wine and 1 teaspoon cornstarch.

For shrimp -- Mix 1 egg white, 1 tablespoon rice wine, 1 teaspoon cornstarch and a little grated ginger.

For deep-frying -- Mix 1 whole egg with 2 tablespoons cornstarch and 1 tablespoon soy sauce. This makes a velvet coating on chicken and pork. SAUCE MIXTURES BROWN SAUCE

This sauce is used with beef, pork, lamb and poultry. It is not recommended for fish or seafood. It is also commonly used for mixed vegetable dishes. 3 tablespoons soy sauce 1 tablespoon rice wine 1 teaspoon sugar 1/2 teaspoon szechuan pepper 1 teaspoon cornstarch 1/2 teaspoon sesame oil 2 tablespoons water

Mix together all ingredients. SWEET AND SOUR SAUCE

This sauce is very good with pork, fish and seafood. It may be used as a dipping sauce for egg rolls and wontons. Some vegetables do well with this sauce, such as carrots, turnips and cabbage. It is not recommended for beef, lamb or liver. 2 tablespoons catsup 3 tablespoons sugar 2 tablespoons rice vinegar 1/4 cup water or chicken stock 1 teaspoon salt 1/2 teaspoon grated ginger 2 teaspoons cornstarch 1 teaspoon sesame oil

Mix together all ingredients. CHINESE CURRY SAUCE

This may be used with almost anything. 1 tablespoon curry powder (use Chinese curry powder if available) 1 teaspoon salt 1 teaspoon sugar 1 teaspoon grated ginger 1 teaspoon soy 1 tablespoon rice wine 1tablespoon cornstarch 1/2 cup water or chicken stock

Mix together all ingredients. OYSTER SAUCE

This sauce is wonderful on beef and chicken, but may be used on almost anything. It is very good on vegetarian dishes. 2 tablespoons oyster sauce 1 tablespoon soy sauce 1/2 teaspoon sugar 1/4 teaspoon pepper 1 teaspoon sesame oil 2 tablespoon water 1 teaspoon cornstarch

Mix together all ingredients. SAUCE FOR STEAMING VEGETABLES 2 tablespoons water or chicken stock 1 tablespoon rice wine 1/2 teaspoon sugar 1 teaspoon salt

After stir-frying the vegetables until they become bright green, add this mixture and cover with a lid. Steam for 2 to 3 minutes. This is helpful when the vegetables are fibrous or tough and would require long stir-frying.