I was watching an episode of America's Test Kitchen which featured a chef from a famous New York City burger house and he was explaining that he uses a combination of boneless short ribs and "flat meat" for his burgers. They went on to explain that some grocers incorrectly label "flat meat" as sirloin tips. So, I began to try to find "flat meat" with no luck. I found "flap meat" but no "flat meat". Could anyone help?