All there is adding a dash of curry to the dish, When ordering in Chinese it is Tomato Beef Crispy Noodle with Curry. The first times I have this dish is when my Uncle order it when I was a kid. That was before the Hong Kong style of noodles but I like it better with the crispy noodles. You are right that is American invention. I tried ordering in Canada and in Hong Kong and they did not understand until I have to explain it.
