Bronx Bomber fans know all about Lobel's world-class steak sandwiches, exclusively available at Yankee Stadium — until now. Located along the concourse beneath Rockefeller Center, the sparkling new spot from the 160-year-old Madison Avenue meatery, is drawing fans-in-the-know, shop regulars and busy Midtown suits — all eager for a bite of the until-now elite ballpark treats.