Alton Brown, the host of "Iron Chef America," fell into the turnip patch just before the show began taping several scenes outside the White House in late October. (The best stuff always happens off camera.) On the episode, which will open the show's new season on January 3 on the Food Network, two pairs of chefs will compete: Cristeta Comerford, the White House executive chef, and Bobby Flay go up against the combined forces of Mario Batali and Emeril Lagasse. In a collision of politics, cooking and popular culture, Michelle Obama will reveal the secret ingredient that the chefs must...