Does som tam taste the same wherever you eat it?
No. The chilies, the seasonings and the way sweetness is added differ. If the aroma of fermentation is unfamiliar, it helps to ask first whether pla ra goes in.
Som Tam · ส้มตำ
If you want something crunchy and tangy, try som tam. It is a salad made by shredding unripe papaya and pounding it with seasoning in a mortar. Sourness and heat soak into the papaya, and it goes well with sticky rice or grilled dishes. In Isan, some versions include a fermented fish seasoning, so if the fermented aroma is unfamiliar, ask which kind of som tam it is when you order.

Sour and spicy seasoning meets the crunch of papaya. In versions with pla ra, a fermented fish seasoning, you can also taste a fermented aroma. Even with the same som tam, the taste changes with how the seasoning and chilies are used.
If you want less heat, say so before it is made.
Som tam is a signature Isan dish and is eaten in many cities across Thailand. Even within Isan, each area has a different kind, so you can compare som tam much as you might compare regional barbecue styles. On a trip to Khon Kaen, eat it with sticky rice and other Isan dishes.
No. The chilies, the seasonings and the way sweetness is added differ. If the aroma of fermentation is unfamiliar, it helps to ask first whether pla ra goes in.
Not necessarily. Some kinds use fish seasoning or shrimp. If you are vegetarian, ask whether you can eat the seasoning and toppings as well as the papaya.
If you want to read more about the food and the regions behind it, these sources are a good place to start. Ingredients and recipes can vary from one restaurant to the next.
Sharing image credit: Vyacheslav Argenberg · CC BY 4.0