Now that’s how to dress in New York during a recession.

For her first visit here as First Lady, Michelle Obama recycled a wardrobe staple. She shopped her closet and picked a Tracy Feith dress that she’s worn before for a meet-and-greet at the U.S. mission to the UN Tuesday afternoon.

Mrs. O sported Feith’s flowered frock on her husband’s first full day in office back in January.

For evening, the First Lady changed into city-perfect cocktail attire – a stunning floor-length navy blue gown from high-end French designer Azzedine Alaia, layered with a corset from her Chicago favorite, Peter Soronen – to deliver a keynote address at the Time 100 Most Influential People Awards at Time Warner Center.

At the podium, Obama’s voice quivered with emotion as she told the crowd she never imagined she’d be a role model for girls around the globe.

“Girls who possibly look at me and see something more for themselves, more than society expects of them. Girls who now think, maybe just maybe, anything is possible,” she said.

“As global leaders, let’s not underestimate the power each of us has to change the world for someone – and let’s not be afraid to try.”

Though the room was filled with luminaries from around the world, most were star-struck to be in First Lady’s company – even old friend Oprah Winfrey, her tablemate at the event. (See more in Gatecrasher, pages, 26-27)

“Seeing as how Michelle is the greatest First Lady we’ve ever known, not to take anything away from the other First Ladies, but I think its so fantastic that she’s tonight’s guest and leads the pack of influentials,” Winfrey told the Daily News.

“I think that we see that Michelle is someone of multi-dimensions, and that you don’t have to be just one thing, you can be many things,” said Diane Sawyer. “In many ways were just getting to know all that she can and will do.”

“She’s very warm. She’s very sane,” said “The View” co-host Joy Behar. “She’s not crazy like some people in politics.”

“Michelle is incredible, I think she’s amazing,” said designer and Beatles scion Stella McCartney, who also made Time’s list. “The half-American in me wants to dress her.”

Other nominees took things more in stride.

On being in the same category as Obama, Whoopi Goldberg quipped, “What does Michelle Obama think about being in the same category as Whoopi Goldberg? That’s the real question.”

adiluna@nydailynews.com

With Michael Saul, Sean Evans and Amanda Sidman

NEW YORK – MAY 5:  U.S. first lady Michelle Obama speaks during the Time’s 100 Most Influential People in the World Gala at Rose Hall – Jazz at Lincoln Center on May 5, 2009 in New York City.  (Photo by Kevin Mazur/Getty images for Time Inc.)