I've been reading all of the posts about Renu Nakorn versus Lotus of Siam with interest. I have eaten at both places (and Id probably give the edge to Lotus). But reading all of these reports has caused me to think about Thai food as it is usually experienced in the US.
I think that a lot of people who have only eaten Thai food in the U.S. think that the degree of spiciness is the main determinant of whether or not a dish is "authentic." This really isn't the case.
The main difference between Thai food in Thailand and Thai food here is the intensity of ALL the flavors - not just how spicy it is. Just like the title of the excellent cookbook by Jeffrey Algord and Naomi Duguid, Thai food is "Hot Sour Salty Sweet." Unfortunately in the US, it is usually just hot and this makes the dishes very unbalanced.
If you order a dish in Thailand - almost any dish - it will be chock full of garlic, chilis, fish sauce, lime juice, ginger and lemongrass. For the most part, Thai restaurants in the US will increase the heat but not the other ingredients, especially the garlic, lemongrass and fish sauce because, apparently, most Americans find these flavors offputting. (When I say a lot of garlic, I mean a lot of garlic - a single portion of thai beef salad might have ten cloves of raw garlic.)
Some people seem to have the mistaken idea that if a dish isn't spicy, it isn't Thai, which isn't at all the case. Sausage for example, whether Issan style ("saikok Issan") or Chiang Mai style ("sai oor") is not particularly spicy. In Thailand either of these dishes - more beer snacks really - would be served with a condiment dish with raw garlic, peanuts and chilis on the side as well as sticky rice. (When I ate at Renu a few weeks ago and ordered the saikok Issan, what they brought out was actually sai oor.)
The salads, or yams, are the spiciest dishes of all, always. Even in Bangkok, the yam section of the menu will frequently not be translated into English in a restaurant because most non-Thais dont like them.
A Thai beef salad ("Yam nuea") in Thailand will be radically different from a Thai beef salad in the US. It will be spicier but that is not the main difference. In Thailand, yam nuea will be composed of fatty beef neck (absolutely delicious!) whereas here it is usually flank, shin or even chuck. There will be about five tablespoons of meat, finely chopped. It will also have about five tablespoons, in equal portions, of garlic, lemongrass and prik kee noo chilis and it will be bathed in equal parts of fresh lime juice and fish sauce ("nam pla"). The salad part will consist of handfuls of cilantro, basil and/or mint, also finely chopped. Everything is finely chopped so you can eat it with your hands, scooping up the salad with either sticky rice or a leaf of some kind, such as basil.
This is a spectacular dish hot, sour, salty and fatty - and very easy to make and you will almost never see this prepared this way in a Thai restaurant in the US, where it frequently looks like an American chefs salad with some beef strips on top and is absolutely awful.
Another thing is, although I personally love Issan food, Issan food is not the cuisine of Thailand, it is one regional cuisine of a country with four very distinct regions. It is the cuisine favored by the people of Issan, Thailand's northeastern region bordering Laos and Cambodia, who are a) ethnically Lao and b) the poorest people in the country and c) who make up most of the service workers in Bangkok. For this reason, it is kind of like the soul food, the down home food and is mainly available in Bangkok through street vendors as opposed to restaurants.
Many Thai people (namely the 46 million Thais who aren't Issan) don't even like Issan food. If you walk into a Thai restaurant run by non-Issan Thais, they probably won't have too much Issan food because it isn't what they eat and they may not even consider it to be true Thai food. This is true even in Bangkok!
It's sort of like walking into a fancy temple of French haute cuisine (LOrangerie, say) and demanding Alsatian food such as sausages and sauerkraut because Alsace-Lorraine happens to be part of France.
Issan by rights should be part of Laos and, like Alsace-Lorraine, it is only through an accident of history that it is part of Thailand. In fact, many Issan people will "identify," as they say in Berkeley, as Lao. The point is, these are two totally separate cultures and cuisines, so you shouldnt assume that all Thai restaurants are going to have Issan food.
The other thing is that Issan food, while delicious, isn't terribly hard to make. However you have to start with the right ingredients (frequently unavailable here) and then simply refrain from screwing it up by adulterating it for American tastes. Issan food is the food that every grandma knows how to make.
The quintessential Issan meal is something you buy walking down the street from a street vendor in Roi Et or Muk Dahan or Surin, all sleepy provincial towns that resemble Bakersfield or Texarkana more than LA or San Francisco. You buy it for the equivalent of thirty or forty cents and you eat it sitting on a little plastic stool on the street while you down a beer or two. It ain't fancy restaurant food and you don't need a chef. You do however need someone who knows what it is supposed to taste like, which brings me to my next point.
One of the problems that I have found with many Thai restaurants in LA is that the Thai employees are almost always Thai-American and if they weren't born here, they left Thailand at a very young age and they themselves may have only a vague idea of what Thai food is actually supposed to taste like even if they speak Thai. They have frequently grown up on Americanized Thai food themselves.
A great place to observe some of this multi-generational interaction is the Thai Wat in the San Fernando valley every Sunday, where you will see older Thai ladies cooking up great authentic Thai/Issan street food and Thai teenagers who have grown up in the valley telling the old women in English that they "don't want anything too spicy or weird." The Sunday food fair at the Wat by the way is the closest to an authentic Thai experience that Ive ever found in the US.
The other thing Ive noticed is that Americans foodies in search of an authentic Thai food experience will typically order every single dish extra hot" or what they imagine to be the Thai style. Meals in Thailand tend to be much more balanced with one or two hot dishes and several others dishes that are sweet or savory. If you go in a Thai restaurant and order everything super-spicy they will make it that way for you (Thai people are nothing if not accomodating) but they will probably be mystified as to why you want to eat a meal that is so out of balance.
Finally, there is a Thai teenager named Nattawud Daoruang who has created two really exceptional Thai sites which may be of interest to Thai food fans. One is called www.learningthai.com, which has an excellent food section and the other is called www.thailandlife.com.
LearningThai.com actually has a food glossary, with the Thai spelling, the English spelling and a Flash module that enables you to click on an item and hear how to correctly pronounce it the Thai word. I would highly recommend it.