The moviemaker is set to reunite with his Iron Man star Robert Downey, Jr. to work the film about a top chef, and he picked up some useful tips as he pitched in with dinner service at the Wolfgang Puck restaurant in the posh Hotel Bel-Air.
Donning a bandana and white chef's jacket, Favreau prepared a prawn dish with sea urchin and salmon roe, and word quickly spread into the dining room about the celebrity chef behind the scenes.
Favreau was mentored by Austrian master Puck, as well as top chefs Roy Choi and David Chang, who at the end of the evening challenged Favreau to prepare an omelette, then laughed and took pictures while he gave it his best shot.
Choi tells The Hollywood Reporter he has been working with Favreau for several weeks: "(He is) in all of my kitchens, working his way through, to see what it's really all about - the whole journey."
The film will also star Iron Man 2 actress Scarlett Johansson, as well as Sofia Vergara and John Leguizamo.