You can’t stop progress: As the A-bomb begat the H-bomb, and Jack Nicholson’s Joker begat Heath Ledger’s, the hamburger ante just went up in New York. Meat purveyor Pat La Frieda, whose revolutionary ground-beef mix has become the standard for the city’s most ambitious burgers, is introducing a superpremium “black label” mix by supplying it to one of the entrants in this fall’s Rachael Ray Burger Bash cook-off in DUMBO on October 10. The proprietary blend will likely be too expensive for any but a few high-end clients, admits La Frieda V.P Mark Pastore. The mix will be a limited series, with each batch numbered for total traceability. “We’re really just bringing it out for a few chefs,” Pastore says, declining to give any names. “But we thought we would debut it at the Burger Bash. That’s where the burger world will meet, and we will be surprised if it doesn’t win. It’s the end product of 100 years of La Frieda burger experience.” The first restaurants to start serving the black-label blend will do so in the fall; we’ll let you know once their identities are released. As for the team with the La Frieda secret weapon? “We’ll never tell — unless they win,” says Pastore.