That's a pretty broad question, especially if you live in an area without an established Chinatown. If you do, it should be easy enough to go there and scope it out. As far as restaurants go, don't be afraid to ask the servers about this. You could also seek out specific dishes. I like to look for a place that has dry friend green beans (or gan bian si ji dou), chongqing chicken, three cup chicken, congee, dandan noodles or mapo tofu on the menu. Also, don't just look for a "Chinese restaurant", look for a "dim sum restaurant", a "hand drawn noodle restaurant" or a "Sichuan restaurant", etc.
If you can't find a decent restaurant, you could try to make stuff on your own. Search foursquare for "Asian supermarket", it will likely carry real Chinese ingredients even if it is primarily Vietnamese or Korean. As far as what to cook, I think https://omnivorescookbook.com/ always comes up with something pretty good. I also swear by the Mission Chinese cookbook. While some of those recipes aren't exactly authentic, they are close enough (and the author explains the ways they differ, like they have a recipe for kung pao pastrami - you're not going to find pastrami in China, but the kung pao part is pretty close).
China is also a huge place that has many regional variations. Just like BBQ in Texas is different from BBQ in Eastern North Carolina, it's hard to say what is or isn't authentic in terms of Chinese cuisine, or what is authentic to a particular regions, etc. I'm sure they're arguing about it over there, too.
If you can't find a decent restaurant, you could try to make stuff on your own. Search foursquare for "Asian supermarket", it will likely carry real Chinese ingredients even if it is primarily Vietnamese or Korean. As far as what to cook, I think https://omnivorescookbook.com/ always comes up with something pretty good. I also swear by the Mission Chinese cookbook. While some of those recipes aren't exactly authentic, they are close enough (and the author explains the ways they differ, like they have a recipe for kung pao pastrami - you're not going to find pastrami in China, but the kung pao part is pretty close).
China is also a huge place that has many regional variations. Just like BBQ in Texas is different from BBQ in Eastern North Carolina, it's hard to say what is or isn't authentic in terms of Chinese cuisine, or what is authentic to a particular regions, etc. I'm sure they're arguing about it over there, too.