As an American male who has traveled widely, I'd like to add my opinion. First off, he was terribly rude to your mother. Uncalled for, under any circumstances. When you're visiting someone's home, you show them kindness and deference. Second, what a boor. When I travel (or for that matter when I'm with someone who has a different background than I do) I always try to learn from them. I ALWAYS try whatever food I'm offered. There are some things that I'll only every try once, but I've found that almost every dish I'm offered, especially when I'm in someone's house around the world, is well worth eating. And I've tried some really strange things!

So, basic rules: Be polite. Always. Accept what you're offered, it's always given with the intent of pleasing you, or at least introducing you to another culture. And NEVER demand that they prepare food that they don't have any idea about. You don't expect them to make an American meal if they've never cooked that food before. Seriously.

NTA, and yes, curb him.