No not American cheese. They don't use really any yellow cheeses in Mexico. On a taco, if there is cheese it's generally Queso Fresco, a white cheese that doesn't melt.

But in Americanized dishes they often add yellow cheese. Shit even at the store they sell "Mexican Blend" bags of cheese with yellow cheese lol

Of course, just because it isn't "authentic" doesn't mean it isn't good. Know the difference sure but you can still enjoy both.

No need to be gatekeepy. Tex-Mex is also delicious!

But some signs:

1. Any kind of yellow cheese is generally not found in "authentic" Mexican.

2. Burritos, no. They do exist up north but are quite different. No rice or vegetables. Nothing like Tex-Mex burritos.

3. Lettuce, diced tomato (other than pico de gallo), sour cream, (or as aforementioned, yellow cheese) on tacos/tostadas is not "authentic". Onions, cabbage, cilantro, lime. Pico or some salsa optional. That's "authentic".

4. "Authentic" tacos don't have hard shells. Flour vs corn tortillas vary by region but tacos are always soft tortillas.

5. Fajitas are an American invention (and they slap, again I'm not here to gatekeep)

6. Nachos as most generally know them, lots of toppings, etc. that's an Americanized thing too.

7. Ground beef. In tacos or otherwise isn't generally a thing. Really beef isn't THAT common an ingredient in Mexico (in the north, a bit more common)

I don’t have a solid answer for what is considered authentic, but growing up in California there are a few things I look for.

• Is the salsa tasty with a nice balance of spice and aromatics? Great chips are a plus, but making them in house is a PITA so I assume most restaurants use a vendor
• Rice and beans are actually delicious. I prefer refried
• trying to remember the last time I had tacos served in a flour tortilla but that would be a red flag. Corn tortillas should be the default or only option
• weird one but I trust a place that does traditional food cost pricing more. $11.40 enchiladas vs $11.25 where the pricing is less rounded

It's the décor, if you can see at least 3 pinatas and 2 sombreros when you enter, you have found the right place.

/J

This is mostly true for the entire US. But not just Texmex, there are a lot of variations. Like the Chipotle burritos that started in San Fransisco.

And not just Mexican food, most food is altered somewhat for the US tastes. That orange chicken at the Chinese restaurant was invented in the us.

I have found what I believe are authentic Mexican restaurants. But we were the only non-Mexicans there and they were cooking dishes like whole fried fish.