In the US, my "old country" Chinese and Japanese friends complaint that the ethnic food is not authentic either. Same with my Indian and Ethiopian friends. The food is great to me, as it's all I've ever know. I was born in Vietnam and raised by parents who cook "old school" so I'm quite a Vietnamese cuisine snob as well.
Here in BA, I've found no authentic Vietnamese dishes outside of my house, but I HAVE found dishes that are good and that I would go back for. The "pad thai" at Sudestada for example, SOOO not pad thai, but good for what it is. Mumbai is a favorite of mine for Indian. The owner is from India. The food has been "diluted" to fit the Argentine palette. We are in Argentina, after all. But the hotness (etc) can be adjusted and, in my experience, the staff is happy to do it. Sarkis for Armenian is awesome. Sure, you have to ask for yogurt sauce, and maybe some of the seasonings are not spot on, but it's good food. As for sushi, my best luck as been at the Okiren Sushi Bar and Restaurant (
http://www.guiaoleo.com.ar/restaurantes/Okiren-Sushi-Bar-Restaurant-6755) in San Cristobal at the Centro Okinawense (
http://www.okiren.org.ar/). Also, Nikkai (
http://www.guiaoleo.com.ar/restaurantes/Nikkai-Asociacion-Japonesa-en-Argentina-125). Both restaurants are hidden from the street, so it takes a bit of perseverance to find them, but it is worth it. Another ethnic place I would recommend, that my Korean friends don't necessarily like, is Bi won in Once.
In the States we have more restaurants to choose from, so our chances of finding something that suits our palette are greater. But don't fool yourself into thinking that what you are used to in the US is close to authentic.
I advocate keeping ethnic restaurants in BA open by patronizing them and opening a dialogue with restauranteurs to help improve your experience . If we boycott ethnic restaurants, we'll be stuck with no options whatsoever outside of parilla and pizza.
