'Top Chef' Alum Leah Cohen Has a Khao -- You Sabotaged My Restaurant!

"Top Chef" alum Leah Cohen -- who placed 6th on Season 5 of the show -- is in dire straits with her NYC restaurant Pig & Khao ... and now she's suing the restaurant's management company, blaming it for all her financial woes.

Leah filed the lawsuit against New York Restaurant Services Group -- owned by famed restaurateur Rick Camac -- claiming she signed a 50/50 business deal with it last year, agreeing to split ownership of her restaurant in exchange for its management services.

Leah says NYRSG agreed to oversee Pig & Khao's operations, including finances, development, marketing, advertising, training of staff, and a bunch of other management-related tasks -- but ended up getting Pig & Khao into a heap of money troubles instead.

According to Leah, NYRSG failed to pay the restaurant's suppliers, its staff, its landlord, and even the Tax Man -- resulting in massive unpaid bills and frozen bank accounts -- but still insisted on paying itself a 3% management fee.

Leah -- who claims to have invested $400,000 in the business with her father -- says the restaurant owes the government $47,283, her landlord is threatening to throw her out, and she's on the brink of losing everything.

She says the restaurant is "clearly failing," and has been operating at a loss pretty much since it opened last fall. (For what it's worth, Pig & Khao has stellar Yelp and Zagat reviews. So check it out.)

She is suing NYRSG for unspecified damages, and wants to terminate their business relationship ASAP. A rep for NYRSG had no comment.