Natalie Portman, a spindly wisp of a girl in a striped turtleneck, is outlined against the window of a midtown Manhattan cafe, with Rockefeller Center Ice Rink behind her. She's a delicate package of woodsy innocence and Audrey Hepburn incarnation--thin arms, heart-shaped face, pink cheeks, ears set high, almond -shaped eyelids with brushy lashes. In the distance, skaters circle fleetingly, a fitting backdrop for this volatile point in the young girl's life. Portman is 14 years old, has three films behind her, and another in the works. Though it appears that her life has not yet changed drastically, it will.

Portman wavers from girl to grown-up. She talks about Yitzhak Rabin's assassination, Anne Frank, vegetarianism, and astronaut doctors in one breath- -and about milk moustaches and Aladdin on Ice in the next. Forgoing a soda or hot cocoa, she requests a more adult beverage, hot tea. With a child's coltish energy, she stirs in the milk, the cup tinkles, and a tan mixture spills over onto the saucer. "I love milk so much," Portman says offhandedly. "I make a point of drinking a glass of milk every day. So now anyone who did those milk ads with the milk moustaches, they're my heroes." With a conspiratorial lift of the eyebrows, she sneaks a few packs of sugar into the mix. "Excuse me," she says sheepishly. "I also like a lot of sugar."

Although unaffectedly natural in real life, Portman can conjure up intense emotion at a second's notice, a gift not lost on French director Luc Besson, who selected the then-13-year-old from more than 2,000 girls for her movie debut, The Professional. In the film, Portman is Mathilda, a precocious orphan who becomes an adolescent gun moll after she is taken in by Leon, a taciturn hit man. In one memorable moment, Mathilda tries to fool a hotel clerk into thinking there is more to the innocent arrangement between her and her laconic mentor (whose favorite beverage, by the way, is milk). Portman was aghast when she saw the scene for the first time. "When I'm like. . ." She pauses. Her eyes brew, and instantly she becomes the dark and troubled Mathilda amidst the Fifth Avenue tourists lunching beside the ice rink. She repeats the memorable line: "He's not my father--he's my lover." She comes back to, squealing with laughter. "I was like, 'Oh my God, I cannot believe I said that!' But it had such great shock val ue. In the movie theater, everyone was kind of like. . ." She gives a look like that of a Mennonite bookseller asked if she carries anything by Anton Le Vey.

No doubt this changeling ability was just one link in the chain of circumstance which led Portman to play Al Pacino's explosive daughter in last year's Heat, and makes her perfect as the girl Timothy Hutton proclaims he will wait ten years for in this month's Beautiful Girls. And Woody Allen recently cast Portman alongside Julia Roberts, Drew Barrymore, and Tim Roth in his next film, a musical, after only one meeting.

"I met him," Portman relates, "I shook his hand. He said, 'Hi, I'm Woody,' and introduced me to the three people who were in the room. I said, 'Hey, I'm Natalie.' He asked me three questions, like, 'Where do you live? How old are you? Are you free for the fall?' "

Portman enjoys acting, but she sometimes wonders how meaningful it is, and still thinks a lot about what she wants to do with her life. She changes her mind each month about what she might ultimately do, but right now, being an astronaut doctor sounds good; evidently her father's work as an infertility specialist has made a deep impression on her. "My dad has helped so many people. You have to accept something that when you wake up in the morning, makes you feel good, just knowing you're gonna go into work and help someone," Portman says earnestly. "With movies, you feel like you're going in, and you get a lot of money, and people see you on TV, but I don't know if you're really helping someone. Maybe I'll find out if you do." Her voice lightening, she adds, "I hope I do, because it's really fun!"