Donning a white smock and white paper hat as required by federal law, I followed [chef Adam Perry] Lang inside these hallowed halls of prime and choice beef. My friend Adam heads to the Bronx at 1:30 AM to visit Master Purveyors, a meat distributor at the Hunts Point Cooperative Market. A big burger fan, Adam wanted to see the beef being ground. I love his photos of the steaks being dry-aged. I only wish he talked more about Master Purveyors and what makes their steaks so good.