Behind every great chef are diligent commis, or assistant chefs. For Chef Richard Rosendale, the chef who won last week’s Bocuse D’Or USA competition, his commis was Corey Siegel, a 21-year-old Jewish trainee chef who works with him at the Greenbrier resort in White Sulphur Springs, West Virginia. The Bocuse D’Or competition is considered the Olympics of cooking, and the USA segment qualifies American competitors for the global contest in Lyon, France next year. Rosendale and Siegel will compete against teams of chefs...