Whenever you have guests from a foreign country with a general dislike or distaste for America, and the conversation turns to how awful American food is, forget trying to explain the hamburger to them. Make them a BLT. The BLT, when made well and even when made with cold bacon in a diner, is in my opinion, the best authentically american sandwich. That and its 95 degrees so I wasnt turning on the oven for love or money...
you'll need 1 lb bacon. I used Oscar Meyer because it was on sale and I think it has a genuinely yummy sweet/salty balance. But if you are in or near the midwest and can get a local 'country bacon' use that (Delicious!!)
1 loaf of the best whole wheat bread you can get
avocado if you like
I assume you already know how to make a BLT, so make one and serve it to your Anti-American friend. Guaranteed to provoke a reconsideration of American food. Dont try to defend McDonalds or American Agribusiness, you cant, just keep frying the bacon.