Tom yum clear or creamy, and why tom kha is not just tom yum with coconut

Tom yum (ต้มยำ) is a hot, sour, salty soup scented with fresh herbs. There are two main styles, and the cook may ask which you want. Nam sai (น้ำใส, “clear water”) is the traditional one: a clear broth, sharply sour and hot. Nam khon (น้ำข้น, “thick water”) gets evaporated milk or creamer at the end, so it turns cloudy orange and tastes softer. Tom kha (ต้มข่า) is a different dish again, built on coconut milk and led by galangal. Know these three and you can order exactly what you like.

Tom yum kung was inscribed by UNESCO as Intangible Cultural Heritage of Humanity in December 2024. The Thai government describes it as a dish of farming communities along rivers and canals, made with herbs that grow close to home.

What goes into the pot

Every tom yum starts from the same herb set, then the versions split at the end.

• Aromatics: lemongrass (ตะไคร้, ta-khrai), galangal (ข่า, kha) and makrut lime leaves (ใบมะกรูด, bai makrut), sliced or bruised and simmered for their scent
• Chilies: bruised bird’s eye chilies (พริกขี้หนู, prik khi nu) for heat
• In the pot: mushrooms (usually straw or oyster mushrooms) and prawns, mixed seafood or chicken
• Seasoned at the end: fish sauce and lime juice go in once the meat is cooked, because long heat dulls the lime
• Nam prik phao (น้ำพริกเผา, roasted chili paste): many cooks add it for colour and a sweet, salty, gently hot note

The herbs you do not eat

First-timers often chew a slice of galangal and wonder why it is so hard. These herbs are not harmful, but they are woody and fibrous. They are there to flavour the broth, and kitchens usually leave them in because they make the bowl look right.

In the bowl	Eat it?	Note
Lemongrass (angled pieces)	No	Fibrous, will not chew through
Galangal (round slices)	No	Hard, sharp and peppery
Makrut lime leaves	No	Leathery, torn for aroma
Bruised bird’s eye chilies	If you can	Very hot; push aside if unsure
Mushrooms, tomato, coriander	Yes	The actual food

Setting the lemongrass, galangal and lime leaves on the side of your bowl is not bad manners. Thais do the same.

Clear or creamy: the difference

Both use the same herbs. What changes is the finish.

	Nam sai (clear)	Nam khon (creamy)
Looks	Clear, or light orange with chili paste	Cloudy, soft orange
What thickens it	Nothing	Evaporated milk or creamer, added last
Taste	Sour, hot, sharp, fresh	Smooth, rich, less sour and hot
History	The traditional style	A newer style, often dated to the 1980s
Good for	People who like it bold, eaten with several dishes	Newcomers to chili heat, or a rounder taste
Milk allergy	Usually no milk	Usually milk, or creamer that may contain milk protein

Sources disagree on when the creamy style began. Some date its popularity to the 1980s; others trace it further back. They agree the clear style is the older one.

A note on creamer: “non-dairy” does not always mean milk-free. Many creamers contain sodium caseinate, a milk protein, and US labelling rules require it to be marked as “a milk derivative”. If you have a milk allergy, assume the creamy version is off the table.

Prawn, seafood or chicken

• Tom yum kung (ต้มยำกุ้ง): the famous one. Many cooks simmer prawn heads or shells for a sweeter broth, and the prawn fat turns it orange.
• Tom yum talay (ต้มยำทะเล) or po taek (โป๊ะแตก): mixed seafood, such as prawns, squid, clams and fish.
• Tom yum gai (ต้มยำไก่): chicken, for people who skip seafood.

The prawn and seafood versions obviously contain shellfish. Even the chicken version has fish sauce, and nam prik phao usually contains dried shrimp. See eating Thai food with a food allergy.

Tom kha is not tom yum with coconut

Tom kha gai (ต้มข่าไก่) uses many of the same herbs, but it is built on coconut milk from the start and galangal leads, hence the name, which literally means “chicken galangal soup”. It tastes rich and slightly sweet, much less sour and hot than tom yum. It was originally made with duck; chicken is now the usual choice, and there is a prawn version too.

There is also a coconut-milk tom yum (tom yum kathi), which people often mix up with tom kha. If you see it on a menu, ask which way the flavour leans.

	Tom yum nam sai	Tom yum nam khon	Tom kha
Base	Broth	Broth + milk or creamer	Coconut milk
Leading scent	Lemongrass, lime	Lemongrass, lime	Galangal
Heat	High	Medium	Low to medium

Worked example: one soup for a table of four

Four friends: two love heat, one handles a little, one is allergic to cow’s milk. You want one pot of soup to share.

1. Rule out creamy first. Someone is allergic to milk, so you are left with clear tom yum and tom kha.
2. Tom kha uses coconut, not dairy, but you would still need to check nothing else was added.
3. Choose clear, less hot. The heat lovers add chili fish sauce or crushed chilies at the table; the mild eater is fine.
4. Say it in one go: “Tom yum kung nam sai, phet noi (less hot), mo fai (in a hot pot). One of us is allergic to milk (phae nom), no milk please.”

Three styles, one ruled out, one question asked, and the heat adjusted at the table instead of in the pot: one soup all four can eat. For more on heat levels, see how to order at a made-to-order stall.

Common mistakes

• Chewing the galangal and lemongrass. Leave them on the side.
• Assuming creamy means coconut. It is usually milk or creamer, which matters for a milk allergy.
• Ordering tom kha expecting tom yum heat. Tom kha is far milder. For bold sour heat, order tom yum nam sai.
• Adding lime while it boils. Cooking at home, squeeze the lime after the heat is off so it stays fresh.
• Sipping straight from a hot pot. The broth in a charcoal pot is very hot; ladle it into a bowl first.

Summary

Tom yum comes in two main styles: clear, which is sharp, sour and hot, and creamy, finished with milk or creamer for a softer taste. Tom kha is a separate dish, built on coconut milk and led by galangal. The herbs in the pot are there for aroma, not for eating. If you are allergic to milk or shellfish, tell the kitchen every time. Next in this series: Thai curries by colour, whether they have coconut, and how hot they run.

Sources

• Tom Yum Kung inscribed as UNESCO’s Intangible Cultural Heritage of Humanity — Government Public Relations Department, Thailand
• Tom yum — Wikipedia
• Tom kha kai — Wikipedia
• 21 CFR 101.4(d), “nondairy” foods with caseinate — Cornell LII