Now that Susan Sarandon's career has again borne fruit, everybody wants to know about the lemons.

"Not very practical," she said yesterday, making a slight face. "Sticky, yes, and they leave a tingling, burning sensation."

Sarandon is 32 years old, and in "Atlantic City," a film that opened here last week, she is introduced at her kitchen sink, carefully cutting up lemons and smearing their juice all over her upper ventral torso. Burt Lancaster is a voyeur at a neighborly window. They become friends, and the movie takes off from there.

She learned about acting at Catholic University drama school, through which she worked her way as a switchboard operator, an art gallery attendant and a seasonal post office worker, and where she and married actor Chris Sarandon. They had both wanted to be actors and stars, and now they both are. They are also divorced.

Persons who remember her from the old CU days use the words "skinny" and "ambitious," but the skinny part is over and done with. As for ambition -- well, she quickly landed the role of Peter Boyle's frizzy and doomed daughter in "Joe" of 1970. After that, she was Janet in "The Rocky Horror Show" and Katherine in "The Other Side of Midnight"; she has appeared in "King of the Gypsies," "Last of the Cowboys" and "The Great Waldo Petter," in which she fell to her death from an airplane wing in a romantic and glamorous way.

She was memorably sexy in Louis Malle's "Pretty Baby," memorably neurotic in the soap opera "A World Apart," and memorably televised in "The Last of the Belles," a network evocation of the early days of F. Scott Fitzgerald. Her most recent film is "Loving Couples," in which she portrays 25 percent of a menage a quatre.

"I've been lucky enough to play just about every stereotype there is," she commented, revealing either a subtle sense of humor or biting sarcasm or possibly just a blissful innocence. It's always hard to tell with actors.

"Atlantic City" was also directed by Louis Malle, and the gossip is or was that she and Malle are or were friends. In answer to the semi-direct question, "What can you tell us about you and Louis Malle?" she replied, "Nothing personal." This was taken as a hint to get on with other matters, such as what she can tell us about Burt Lancaster, who is 67 and the star of the picture.

"Well, he was pretty patient for such an established actor," she said. "He has a real sense of what works in front of the camera. After the first day, when he realized that I knew what I was doing, things went smoothly. Sure, we became friends. But I don't know that he was accessible to become a close friend with, really."

As far as the lemons go, Sarandon said, there is a perfectly logical reason for them in the plot. It is also no accident that the old resort town was being torn down around them during filming.

"The movie is about rites of passage, and Atlantic City was going through its rite of passage, too. Gambling was coming in, and the trade-off between prosperity and posterity was obvious. Some of the nice old places where we shot, when you came back the next day they were just gone. Demolished. The wonderful log cabin on the beach where the seduction scene takes place was destroyed right after we finished with it.This was two years ago, of course."

Now that Susan Sarandon has made it in her chosen field, she is of course totally in control of her future.

"No I'm not, " she said. "The movie business isn't like that, especially at this time. There are only probably six actors in control of their careers, and they're certainly all men. Projects are continually talked up, and then put on hold these days."

Sarandon's next movie will be an adaptation by Paul Mazursky of Shakespeare's "The Tempest," which will also feature John Cassavetes, Gena Rowlands and Raul Julia. After that, she's supposed to film the play "A Coupla White Chicks Sitting Around Talking," directed by Jack Lemmon and with Jill Clayburgh as her co-star.

Sarandon was in "White Chicks" off Broadway, and like many movie actors she is at no loss to describe the difference between stage and screen.

"It's the difference between making love to yourself and making love to someone else," she exclaimed. "Movies don't provide any instant gratification at all. Making them is very slow, and there's a lot of waiting around. But on a stage it's overwhelming. You and the audience become completely involved, laughing and crying together and if when it's over they applaud, there's no way to avoid believing that you contributed to it. You say to yourself, 'Hey, I have to be responsible for at least 50 percent of this!" In a movie, you never know what makes a success.

"The funny thing is, before I did 'White Chicks' on stage I never took my own contribution really seriously.There didn't seem to be any real reason to. But 'White Chicks' proved to me that I was good."

So did the Canadian Cinema Genie Award she received as best foreign actress for "Atlantic City." "It's my first award," she said. "There's nothing like an award to make your humility go out the window."

Humility, when shut up in the hothouse of the soul, often turns to envy and bitterness, and there is no reason for Susan Sarandon to risk that. She is quite lovely, with an upturned nose and a slightly tentative chin that gives her face a character of inquisitiveness not found in more porcelain beauty. Her eyes are orbicular. This is not praise but clinical description.

She is the first-born of nine children of a New York stockbroker, and she grew up in Metuchen, a New Jersey suburb among suburbs, and now, frankly, she is rolling in dough ("It literally costs me hundreds of thousands of dollars to do a play, because you make your money in movies, not theater") and has taken the time to form her own improvisational troupe.

"We call our group 'The Group,'" she explained, more or less agreeing that things are going well for her. "Peter Boyle is in it, and Richard Dreyfuss, and Tom Noonan and Brooke Adams and a bunch of others. There's no audience, just us. The funny thing about being well-known is that you don't dare change. So this is a place to stretch yourself, to take risks."

It's the risk part that keeps Sarandon acting, and not climbing the ladder to the next rung, the one marked Director.

"I thought about if for a while, but I don't really have the temperament," she said. "Directing is about control. Acting is about controlled folly, about being on the brink. You just have to keep yourself intentionally off balance, to be good."