Have you tried Philly steak poutine at Elgin Street Diner (Ottawa)? My personal favourite of all the Poutine's tried in Quebec and Ontario. And I have had a lot of poutine in my lifetime thus far, no stroke or heart attack yet.
TRying to think of the greatest barstardization of ethnic dishes. Maybe Pizza? Also, I guess chinese-style fried chicken became General Tso chicken..
Theres always Nachos! They were originally made by some Mexican bartender who wanted to entertain his american lady guests so right from the start they werent really mexican. Originally they were home-made dried tortillas + cheese + jalapenos. Now you got Nachos Grande.