Mira Nair knows that her best movies have been the ones that are the most challenging, independent and personal, films such as "Monsoon Wedding" and "Kama Sutra: A Tale of Love." But it's hard to resist Hollywood's siren call.

When Focus Features offered Nair the film version of William Makepeace Thackeray's ladder-climbing classic "Vanity Fair," the Harvard-educated Indian director just couldn't say no.

"Since I was 16 I have loved this novel," Nair says.

The film, which opens Wednesday, is both ambitious -- an 18th-century period piece with a $23 million budget -- and sprawling. The shoot hit 90 locations on two continents. Reese Witherspoon stars as go-getter Becky Sharp in an adaptation of the Thackeray story written by Oscar winner Julian Fellowes ("Gosford Park").

"I spent two months mapping what I wanted, a democratic swirl of the milieu of that time, the love story between Becky and Rawdon, and the intersection between colony and empire," Nair says between bites at a restaurant on Sunset Boulevard. "It's a story of the most exquisitely tyrannical order, and that tyranny Indians understand even better than the English."

After spending the summer with her family in Kampala, Uganda, happily gardening and writing, the 46-year-old director has just returned stateside. As she wolfs down her first Indian-restaurant meal in months, she beams. "This is so comforting," she says. Nair looks as vivid as her movies: shiny black hair and eyes, crimson mouth, royal green tunic and gold pants, earrings and pointed sultan slippers.

"Becky Sharp was like me: She didn't like the cards that were given her, [so] she made her own deck," Nair says. "She is utterly modern and timeless. There are hundreds of Becky Sharps in Grand Central Station going home, having tried to ascend in the city every day."

Nair's own ascension came with 1988's verite-style "Salaam Bombay!," her feature debut, which was nominated for a Best Foreign Film Oscar. Next came the steamily sexy "Mississippi Masala," starring Denzel Washington. "People told me directly that if I had a white protagonist it would be much easier," she says, but she doggedly pursued her own concept of a multiethnic romance: When she got her first notes on the movie from Cinecom Pictures, the anti-authoritarian filmmaker shot off a response to executive Bart Walker. "I got your white-bread points," she wrote back. (Today Walker is Nair's agent.)

"Mississippi Masala" became a critical and art-house hit, and the Samuel Goldwyn Co. chased after Nair to make "The Perez Family," with Marisa Tomei and Alfred Molina. The offer came at a vulnerable moment, she recalls. She was living in Johannesburg with her professor husband and infant son, wondering how she would mount another film.

So she grabbed at the chance to shoot the immigrant saga of Miami Cubans. "I understood this seesaw between memory and exile," she says.

Nair lost control of the movie in the editing room. "It's like horse- trading," she says. "They previewed it and began to think it was a broad comedy. And I was saying, 'Let's preserve the rhythm.' " The film flopped.

Since then, Nair has gone her own way with films including "Kama Sutra," the HBO movie "Hysterical Blindness" and "Monsoon Wedding," which delighted audiences in the summer of 2002.

Now she's so much in demand that she can't keep up with all the things that people want her to do: A cinematic love poem to Paris? Tony Kushner's "Homebody/Kabul" for HBO? A Broadway musical of "Monsoon Wedding"? An African American comedy take on a Bollywood blockbuster?

So she does what she wants. Which right now means wiping her plate with fresh-baked nan.

And as a distraction from the stress of releasing her biggest feature, she's embarking on another cross-cultural literary film adventure, Jhumpa Lahiri's novel "The Namesake." The film shoots this December in Calcutta, Cambridge, Mass., and New York. "I have to balance myself," she says. "I felt the need to see my own people though my lens."

Mapping the intersection of colony and empire: Reese Witherspoon and Indian director Mira Nair on the set of "Vanity Fair," which opens Friday.Jonathan Rhys-Meyers and Reese Witherspoon in the 18th-century period piece "Vanity Fair," which filmmaker Mira Nair, below, calls "a story of the most exquisitely tyrannical order."