Thanks for all the suggestions! I especially loved the idea that we should think about regional cooking instead of national cooking--I may not be able to think of an American dish but I can sure come up with Cajun dishes! Looking at your suggestions, we quickly realized that we were going to be constrained by what ingredients are available here. We were thinking of gumbo for a while but Ruth pointed out that everyone would think it was an African stew (another interesting commentary on America's culinary tradition!), so in the end, we picked macaroni and cheese.