Specialty somtum food-carts exist on every street [thanon] and lane [soi] in Bangkok. Somtum is eaten with sticky-rice, and is a better waker-upper than smelling salts.
INGREDIENTS
1. One raw, green [immature] papaya, peeled and shredded.
2. One decent handful of small, red chilli (#1)
3. Several cloves of garlic, unpeeled
4. 2 or 3 small tomatoes, quartered
5. 2 or 3 whole limes, quartered
6. Quarter cup of dried shrimp
7. Cup of rotted fresh water crab (or rotted fish) (#2)
8. Quarter cup of fish sauce
9. Half cup of [secret recipe] somtum sauce (#3)
10. Quarter cup of roasted peanuts
PREPARATION
1. Throw ingredients 2-10 into a large mortar, and pestle enthusiastically for 30 seconds or so (#4)
2. Heave in the shredded papaya and pestle a bit more
3. Taste. If the skin immediately blisters and peels off your tongue, then add a teaspoon of sugar, and pestle a bit more
4. Empty mortar onto a large ceramic dish, place in the middle of the floor of the verandah; invite everyone to squat around the bowl and "dig in". (#5)
That, folks, is the genuine article, Isaan style! Enjoy!
NOTES
#1. It is advisable to use red chilli. Green ones taste the same, but you cannot see them so easily, and so risk forking a whole lot of them into your mouth, and suffering untold pain.
#2. I am allergic to crab, so cannot tell you what rotted crab tastes like. I can tell you rotted fish tastes about as bad as it smells. If you can't summon the courage to try either, then here is a work-around...substitute the rotted aquatic creatures with raw green beans, broken into bite size pieces, and be sure to let your Thai friends understand you have done this because you are allergic to sea-food (they won't believe you for a second, but will allow this face-saving gesture).
#3. No-one can tell me what this is. I suspect it is the liquid remains of rotted aquatic critters. I believe it may be acceptable to substitute it with fish or chicken stock, and a double shot of fish sauce.
#4. Thai cooks have a pestle in one hand and a wok tool in the other; they pestle twice, then scoop once to mix up the pulverised material...repeating for about 30 seconds. Remember to shut your eyes while performing this operation or the fumes will dissolve your eye-balls.
#5. Must be ceramic...metal or plastic will dissolve and so cause you to lose face. Verandah is best as there is more likely to be a decent flow of air, and so neither you nor your dinner guests will be overcome by the fumes...if you must eat in-doors, then set up the biggest fan you can and activate the turbo-boost function.