NEW YORK. Goodbye Crystal Room and champagne. Hello tacos and beer. Central Park’s famously frilly Tavern on the Green is going downscale with four food carts set to move onto its terrace on Oct. 15. Pera Mediterranean Brasserie is bringing what may be the country’s first Turkish taco truck, along with the Rickshaw Dumpling Truck, Van Leeuwen Artisan Ice Cream and Ladle of Love’s stews. Tavern’s new leaseholder backed out this summer after failed negotiations with the restaurant’s union.