I generally have an issue with the term "authentic" when it comes to food. In Thailand there are almost certainly thousands of takes on what Drunken Noodles are, if that is even a traditional Thai dish and not just an exported recipe developed for the taste buds of people outside Thailand.
Any traditional dish is made countless ways. There is really no such thing as "authentic" in my opinion. The best that can be done is to make something that tastes good and is desirable by enough of the people in the location it is made to make it reasonable to put it on a menu.
Wanting something "here" to taste like it came from "there" is not unreasonable, but it's also frequently unobtainable. The local supply chain, local ingredients, etc, are all going to have an impact, but the biggest impact will always be commercial viability. What will people "here" eat, what will they pay for? You can't force food on customers and just yell at them about authenticity. You have to offer things they want to eat.
I don't really care if the Thai food I eat in SLC is the same as the Thai food in Thailand (or Portland). What I care about is if the food I'm eating tastes good to me. I can certainly try to better understand Thai cuisine and get closer to what people in Thailand enjoy. If that is my goal I'm far more likely to find success making that food myself, in my kitchen, sourcing ingredients diligently according to the standard I'm attempting to achieve. Short of that, **** holding a commercial restaurant to a standard that would bankrupt them.
Was that directed at me? If so, I never said "authentic" and clearly delineated what I was looking for (plenty of sauce, fresh thai chiles (fresh thai basil is good too).
I've lived in NorCal, Portland, Chicago, DC, and they all have restaurants with decent Drunken Noodles, and the recipe/flavor is essentially the same. Hell, I even found a decent version in Spokane near Gonzaga. I do make my own, but find it is cheaper for me to get from a restaurant as the local Thai grocery is expensive.
I travel to Utah frequently for work, and have been mostly disappointed with the Drunken Noodle offerings in Utah. One place didn't even use rice noodles. I am sure there are decent options, but don't know where, which is why I asked. I've tried a few of the top star Google/yelp rated places, and many dishes were good, but the Pad Kee Mao has just been ok at best, just not good flavor. I'll try Sawdee next time I'm in town. Thanks for the recommendation.
And as far as Bangkok versions, I tried probably 15 different versions, and all were very similar (maybe the rest of the country is different, but I doubt it). The main difference with the USA versions is the price (when I lived in Bangkok for a summer it was about $2.00 U.S., the only outlier being Jae Fai, which was almost $25 U.S. at the time, and it wasn't worth the hype-small portion, not worth the price or hype (Michelin rated shack, advanced reservation or early a.m. waitlist, which is what we did) and the level of spice. I ordered mild everywhere in Bangkok, and order medium to hot almost everywhere in the U.S. The one outlier is Baan Thai in Portland. Anything above mild is crazy hot (and they use fresh thai chilis). And they warn you.