Take-out Chinese food, long a staple of the American diet, is now available in the Republic. For the equivalent of $5 one can drop by the North gate of the Heping (Peace) Duck Restaurant and pick up a whole, cooked peking duck packed in an attractive box, complete with carrying handles.

Most Western visitors to the Chinese capital are probably more familiar with the Heping's front door, where buses line up every night of the week during the spring and autumn tourist season. The fourth and newest of the duck restaurants in Peking, the seven-story structure is nicknamed "big duck" or "the duck factory" for its ability to serve groups of 600 or more people in a single room. Also, the large-scale roasting is said to be done automatically, but restaurant officials decline to confirm this widely held belief.

The 2.2 pound duck-in-the-box, packed by the China National Cereals, Oils & Foodstuff Import Corp., does not include all of the amenities received by those who sit down at the table. Web foot and beak soup and sliced liver don't make the fast food version. The traditional sauce and thin pancakes for wrapping the meat may be purchased for an additional 50 cents. On the other hand, you don't have to applaud the cook when the bird is delivered and the cost is about half.

According to Yang Lian Rui, manager of the Heping, the restaurant has been offering the take-out service since 1979, when it opened, but it is only in recent months that it has caught on. He sells about 100 a month, mostly to foreigners or Hong Kong Chinese, because of the price. Customers can either walk in off Xuanwumen Street anytime between 10 a.m. and 8 p.m. and wait 20-45 minutes for the duck to be cooked, or call the day before and have it ready on arrival.---

Take-out Chinese food for Chinese citizens is also picking up, according to the Peking Evening News. Chui Hua Lu, a restaurant on busy Wangfuing Street that specializes in food from Shandong Province--one of the four great regional cuisines of the Middle Kingdom--has recently begun offering the service. Jiaozi, dumplings filled with meat and vegetables, have long been a staple of Chinese take-out food.

As with many things in China and about China, a certain amount of controversy surrounds the Peking duck. For example, New York's Mayor Koch recently suggested that the way the fowl is prepared in China--hung to dry in the open air and suspended over a very slow fire to roast--is superior to the method used in the United States. A special state law was passed in California, with the strong support of then Gov. Jerry Brown, to permit Chinese restaurants in Los Angeles to prepare ducks in the traditional Peking style, despite local health regulations on refrigeration and slow cooking.

More serious criticism has been lodged about the force feeding of the ducks, who are regularly dosed with a rich mash mix, through a pressurized pipe . A recent article in the English language newspaper China Daily took note of such concern, reviewing the origins of the delicacy. Citing a Ming Dynasty (1368-1644) book titled "A Glutton's Culinary Talks," the article points out that Peking duck was actually developed in the city of Chang'an (now Xi'an), capital of the Tang Dynasty (618-907). In those days the fowl were roasted alive, suspended in an iron cage above a slow-burning charcoal fire. As the birds began to heat up they were fed a mixture of vinegar, honey, malt, ginger and salt from a copper bowl inside the cage.

The China Daily article concludes: "Pet-loving Westerners sometimes complain about the force feeding of Peking ducks. Now that they know about this primitive method, are they going to stop appreciating this special Chinese dish? One old proverb may help them out of the dilemma. Mencius once said: 'Gentlemen keep away from kitchens.' "

(The same paper carried a story a few days before about the sentencing of a panda-eating peasant from Sichuan Province, who will be spending the next two years in prison for trapping, skinning and butchering a giant panda that was wearing an electronic monitoring tag placed on it by wildlife protection officials.)

But even outside of the kitchen, in the colorful box that carries the legend, in English and in Chinese, "Well-Known Roasted Peking Duck, Crisp, Tender and Delicious," below which is noted "Content: One Duck," at least one controversy remains. That is the "fat-and-grease" issue, perhaps the primary reason why duck is not everyone's cup of tea. Grease is, alas, a potential given with each bird, even when taken out. If carefully prepared, most of the fat will cook out, but each duck is a different story. You just take your chances.