With Reporting By Josh Horowitz

Robert Downey, Jr. has mastered just about everything imaginable. But according to "Chef" director and star Jon Favreau, there's one thing the superstar, who has a brief but memorable turn in the new movie, needs to work on.

"Downey's not a cook," Favreau told MTV News. "He's a singer, he's a writer, he's an artist, so he's definitely a jack of all trades."

Ok, so Iron Man's no Iron Chef. Who in the star-studded cast, which also includes Scarlett Johansson, Sofia Vergara, John Leguizamo, and Dustin Hoffman, is best in the kitchen?

"John's worked the hardest," Favreau said. "He staged in kitchens in New York, and I was training here. And so together, we were able to look like we could work a food truck."

The two kids from Queens the best cooks in the cast? That actually doesn't sound too surprising. And Favreau said that for him, cooking was something that's now taken on a much bigger role in his life.

"For me, I've really taken it on as a hobby now," Favreau explained, "and I'm going to keep going with it."

Check out "Chef," in theaters today (May 9).