Som tam styles: tam Thai, tam pu, tam pu pla ra, tam sua and fruit tam
Som tam is not one dish. What goes in each style, how it tastes, how to order heat by counting chillies, and how to pick pla ra and crab safely.
- Tam Thai is sweet and sour with peanuts and dried shrimp. Tam Lao and tam pu pla ra are salty and funky with fermented fish. Tam sua adds rice noodles.
- Som tam is pounded one mortar at a time, so you can order heat by chilli count, such as one chilli, which is clearer than 'less hot'.
- Thailand's Department of Disease Control lists som tam with raw pla ra as a liver fluke risk. Choose cooked pla ra; lime juice does not kill the parasite.
- Raw pickled crab or rice-field crab in tam pu carries a lung fluke risk. If unsure, order tam Thai or ask for cooked crab.
Som tam is shredded green papaya pounded in a mortar with chilli, garlic, lime and seasoning. A single som tam stall can offer a dozen versions, and what changes the taste most is whether the salt comes from fish sauce or from pla ra (fermented fish), and what else goes in. This article separates the five styles you will meet most, shows how to order the heat precisely, and covers what to know about pla ra and crab before you order.
The wider picture of Isan food is in Thai food by region. This one goes deep on som tam only.
The five common styles
- Tam Thai (ตำไทย): yardlong beans, tomato, dried shrimp and roasted peanuts, seasoned with fish sauce, palm sugar and lime. Sweet and sour, no pla ra. The easiest start if you have never had fermented fish.
- Tam pu (ตำปู), or tam Thai with crab: tam Thai with crab added, usually salted pickled crab or small rice-field crabs.
- Tam Lao (ตำลาว) and tam pu pla ra (ตำปูปลาร้า): seasoned with pla ra sauce. Salty, deep and clearly funky. Tam pu pla ra is the same with crab; some stalls shorten it to “tam pu pla”.
- Tam sua (ตำซั่ว): som tam with khanom jeen rice noodles tossed into the mortar. Usually the pla ra version, and more filling because of the noodles.
- Tam phonlamai (ตำผลไม้), fruit tam: mixed fruit instead of, or alongside, papaya, with chilli, lime, fish sauce and palm sugar. Usually no pla ra.
| Style | Salt from | Extras | Main taste |
|---|---|---|---|
| Tam Thai | fish sauce | peanuts, dried shrimp | sweet, sour |
| Tam pu | fish sauce | crab | sweet, sour, saltier |
| Tam Lao / tam pu pla ra | pla ra sauce | crab (tam pu pla ra) | salty, deep, pungent |
| Tam sua | usually pla ra | rice noodles | salty, deep, filling |
| Fruit tam | fish sauce | mixed fruit | sour, sweet, fresh |
Every stall has its own recipe. The table shows what is common, not a rule. If you are not sure whether a plate has pla ra or peanuts, ask every time.
Order heat by counting chillies
A som tam stall pounds each order in front of you, which means you can control heat more finely than almost anywhere else. The cook counts fresh chillies into the mortar. The words that work are “phrik met diao” (one chilli), “song met” (two) or “mai sai phrik” (no chilli). That is clearer than “phet noi” (less hot), which every stall reads differently.
The heat comes from fresh chillies being crushed, and the longer they are pounded the more heat comes out. If you are sensitive, ask for the chillies to be pounded lightly or left whole.
Worked example: three people, one mortar is not enough
Three friends: the first loves heat, the second can take a little, the third eats no chilli and is allergic to peanuts.
- One mortar can only have one heat level. Pound it for the first friend and the other two cannot eat it.
- Mortar one: “tam Thai, phrik met diao” (tam Thai, one chilli) for the first two to share. The first friend asks for fresh chillies on the side to bite with it.
- Mortar two: “tam Thai, mai sai phrik, phae thua lisong” (no chilli, allergic to peanuts), and ask the cook to wash the mortar first, because it was just used for peanuts in mortar one.
- Add grilled chicken and sticky rice for everyone to share.
Result: two mortars at two heat levels (1 chilli and 0 chillies), and the third friend gets a plate with neither chilli nor peanuts. If that friend’s allergy is severe, read food allergies and Thai food first, because the shared mortar and pestle are the main risk.
You can always add chilli to som tam, but you cannot take it out. At a new stall, start low and ask for chillies on the side.
Pla ra: raw versus cooked
Pla ra is freshwater fish fermented with salt and rice bran. The issue is that some white-scaled freshwater fish, such as the carps used for it, can carry the larvae of the liver fluke Opisthorchis viverrini. Thailand’s Department of Disease Control lists raw pla ra and som tam with raw pla ra among risky dishes, and says liver fluke is the main cause of bile duct cancer, which is common in Isan and the North. WHO notes the infection comes from raw, undercooked or fermented freshwater fish.
A figure from Thailand’s FDA makes it concrete. A 2016 survey checked fish used for pla ra and pla som from 73 markets in 20 northeastern provinces and found the parasite in 7 samples: 7 ÷ 73 ≈ 9.6%, or roughly one in ten.
The FDA’s advice is to cook it, for example boiling at 90 °C for 5 minutes, or freezing at -20 °C for 24 to 48 hours. Salt and long fermentation reduce the larvae but are not treated as a substitute for cooking. As for lime juice, the Department of Disease Control says the belief that it kills the larvae is wrong: it only changes the colour of the flesh.
Ask the stall: “nam pla ra tom suk mai?” (is the pla ra sauce boiled?). Most can tell you. For bottled pla ra, the FDA says to look for the food registration number inside the Thai FDA mark.
Pla ra is also very salty. WHO recommends adults keep sodium under 2,000 mg a day. Do not drink the liquid left at the bottom of the plate, and if your doctor has told you to watch salt, ask for “pla ra noi” (less pla ra) or order tam Thai.
The crab in tam pu
The crab in som tam is usually salted pickled crab or rice-field crab, not cooked. The US CDC says freshwater crab or crayfish eaten raw, undercooked, pickled or salted can transmit lung fluke (Paragonimus), and lists Thailand among the countries where it occurs. CDC advises cooking freshwater crab to at least 63 °C (145 °F).
The safer way to order: ask whether the crab has been boiled. If not, or the cook is not sure, skip the crab and order tam Thai, or a pla ra version made with cooked pla ra.
Common mistakes
- Ordering just “som tam”. Each stall has a different default; some make tam Thai, some make the pla ra version. Name the style every time.
- Thinking tam Thai has nothing to watch. It has no pla ra, but it has peanuts, dried shrimp and fish sauce. Peanut or shellfish allergies must be stated.
- Believing lime or salt “cooks” the fish. The Department of Disease Control says sour and salty seasonings neither cook food nor kill parasites. Only heat works.
- Matching your friend’s heat level. The stall can count chillies for you. Use that, and split into separate mortars when heat tolerance differs a lot.
Summary
Som tam styles differ in their salt. Tam Thai uses fish sauce and tastes sweet and sour, with peanuts and dried shrimp. Tam Lao and tam pu pla ra use pla ra and taste salty and deep. Tam sua adds rice noodles. Fruit tam is fresh and usually has no pla ra. Order heat by counting chillies, ask whether the pla ra is boiled, and be careful with crab that has not been cooked. Next in the series: larb, nam tok and grilled chicken.
Sources
- Department of Disease Control warns on raw freshwater fish dishes and liver fluke (Thai) — The Standard
- Thai FDA: choose cooked pla ra and pla som to cut liver fluke risk (Thai) — Thai PBS
- Opisthorchiasis (Q&A) — World Health Organization
- About Paragonimiasis — CDC
- Salt reduction (fact sheet) — World Health Organization
- 10 Must-Try Isaan Dishes — MICHELIN Guide
FAQ
What is the difference between tam Lao and tam pu pla ra?
The seasoning is almost the same, both built on pla ra (fermented fish) sauce. Tam pu pla ra adds crab. Some stalls use the two names loosely, so ask whether it has crab and what kind.
Can I eat som tam with a peanut allergy?
Tam Thai normally has roasted peanuts, and stalls often pound many orders in the same mortar. Say you are allergic (phae thua), not just 'no peanuts'. With a severe allergy, talk to your doctor and choose another dish when in doubt.
Pla ra is fermented for a long time. Does it still need cooking?
Yes. Thailand's FDA says salt and long fermentation reduce the larvae, but its advice is still to cook it, for example boiling at 90 °C for 5 minutes.
Ingredients and heat vary by kitchen and recipe. If you have a food allergy, ask before you order, every time.