Down-on-her-luck protester Tracy Postert spent 15 days washing sidewalks and making sandwiches at Zuccotti Park — then landed a dream job at a Financial District investment firm thanks to a high-powered passer-by who offered her work.

“I never thought I would be doing this,’’ Postert admitted to The Post.

The Upper West Sider, who has a Ph.D. in biomedical science specializing in pharmacology, was unemployed and had all but given up on finding work in her preferred field of academia when she joined the movement in October.

She held signs that read, “Reagan sucks,” and, “I’ll vote after the revolution.”