In an effort to replicate In-N-Out's famous burger for his Lure restaurant in Soho, Chef Josh Capon found himself doing some undercover work to unlock its mysteries. After sneaking into the kitchen at a Las Vegas branch of the west-coast only fast food franchise, Capon reported back to NBC New York with his findings:
"After the patty goes on the grill, smear just the raw side with a healthy dose of mustard before flipping. The Dijon flavor cooks off but the application deepens the flavor of the meat."
Some impressive detective work, but not exactly a trade secret; a quick Google search for "animal style" could have saved Capon a trip to Vegas.