POOR Mak Donna. How can she maintain her haughty dignity when Lemon Pie is wearing exactly the same dress? And what about Madam, the shy but beautiful traffic warden? Could a rich yuppie like Gary fall for a girl like her? Burning questions of the day indeed. But we're not talking Dallas or Dynasty here. This is San Miguel Street - a Hongkong soap opera in 30-second instalments. While other television advertising campaigns feature diamond-encrusted watches and glamorous women who exclaim, ''Oh, it's him!'', San Miguel Street represents life at the local dai pai dong, where beer and roast goose are served to all-comers. Essentially, the ad is Cheers Hongkong-style, with people from all walks of life gathering at the mythical Sang Kee Restaurant. And what makes this especially intriguing is the fact that most of the characters in San Miguel Street are portrayed by real people, not actors. Take Sang, the owner of the restaurant. He is W. C. Leu ng, a businessman who runs a printing outfit. Mak Donna, the karaoke singer, is played by Eda Ko, a flight attendant with Cathay Pacific. Henry Cheung, alias Ah Lung, the restaurant's cook, does lighting for the ads. But that doesn't mean the cast aren't celebrities. Since the campaign kicked off last September with a two-minute pilot, all concerned have become famous in their own right. ''When I'm walking around, people recognise Mak Donna - old men, little boys, everybody,'' Ko said. ''They're very friendly and I appreciate it. People have me in their memory because the character's quite obvious - she's fashionable, young and I enjoy playing her.'' Leung went one better. ''Out on the street, people call me Sang,'' he said. ''Even in Los Angeles, where I was recognised from articles in Chinese magazines, they asked me if I was the boss of the goose restaurant.'' Mark Reis, who plays Gary, said: ''A lot of people know the lines in the commercials. I walk past and someone might say 'Give me a chance'. Not just women - also men!'' ''Give me a chance'' is the line Gary gives Madam as she is about to issue him with a parking ticket. She shyly repeats it because she finds him attractive. And, while Reis insists he is not a sex symbol, he does get teased about it at work at the Cathay Pacific Training School. But the funny thing is neither Ko, Leung nor Reis seem particularly interested in becoming professionals (Reis has turned down commercial offers) - even though there may be good money in it. Look at Michael Chow, for instance. He is the muscular, smiling character with the shades who has figured in San Miguel's ads over the past few years. As an actor, he finds himself playing the ''Michael'' stereotype in some Cantonese feature films. ''Most Hongkong people would shy away from being on television,'' said Stoney Mudd, creative director at McCann Erickson - the advertising agency which created San Miguel Street. Be that as it may, the series' director, David Tsui, of Moviola Productions, often prefers to use non-professional talent. In fact, his casting agency is always searching for new faces. ''This is the Hongkong situation,'' he said. ''Most professionals are overexposed, and that undermines credibility. So we send people into the streets, the bars, the restaurants. If someone is reluctant at first, we leave them a card. Sometimes, after second thoughts, they will come around.'' Logistically, this makes the job even tougher. And San Miguel Street was an ambitious project from the outset. Consider the premiere episode. Through two minutes of an uncut tracking shot it was necessary to choreograph an elaborate plot to establish all of the original characters. It took about 30 takes. Mak Donna, in particular, was problematic. Ko had to first appear in casual clothing and then reappear a short time later with fresh make-up, a new hairstyle, and a completely different outfit. ''It was a big challenge,'' Ko said. ''It was a hot summer day in August and I had to change in 28 seconds. We did a long rehearsal. At first, they couldn't do up my dress in time and my back would be exposed.'' Since then, the making of San Miguel Street has become more streamlined. There have been a total of 10 episodes already. But this ad, like the soap operas it apes, relies on good ratings if it is to survive. ''Whenever we're on the air, we're usually in the top five in terms of recall,'' Mudd said. ''This is the first campaign to both capture Hongkong and take pride in Hongkong. It's got real legs, and that's why we're happy with it.'' ''I think people identify with the characters,'' Tsui said. ''The stories are lightly humorous - it's an escape from most TV commercials. We keep it realistic without looking at the dark side of Hongkong.'' Coming next to the Sang Kee, a happy-go-lucky bunch of triads? Stay tuned, folks.