According to the Daily Mail, Ramsay recounted that when he moved to the United States in 2004 he had lunch with a Los Angeles Times reporter. After the lunch, their server asked if they'd like their dishes to go.
“She boxed a Caesar salad," Ramsay told the audience. "And I said to her: ‘Do you have any idea how shit a Caesar salad tastes 24 hours later? What will you do with that f*cking thing?’ And she said, ‘I’m going to eat it.'
"'I said, 'But it's been dressed. We dressed it 20 minutes ago; it's sat there for 25 minutes. Why would you eat that?' She said, 'It's delicious.'
"'That's when I knew Americans knew f*** all about good food. Right there and then.'"
Given the context, he was probably partially kidding. But if you want to take this point up with him yourself, remember that you can now enable Ramsay on Alexa. He won't be able to hear you, but at least you can feel like you're yelling at him for once.