If you love Thai food you will undoubtedly be familiar with Tom Yum as it is Thailand’s quintessential soup but there’s a new kid on the block that has risen to popularity in Thailand. The main difference between these two soups is that the original known as Tom Yum Nam Sai ต้มยำน้ำใส has a clear broth whereas Tom Yum Nam Khon ต้มยำน้ำข้น is creamy. This creamy element is evaporated milk although you can use cream, milk or coconut milk. In fact, some people favour coconut milk which is also delicious but in this recipe I prefer evaporated milk because it is neutral and does not overpower it. If you are looking for a Thai coconut soup I recommend Tom Kha Gai.
As with most Thai soups, remember that the aromatics (lemongrass, galangal, kaffir lime leaves) are not meant to be eaten but as served in the bowl for flavour and a visual representation of its ingredients.
500g fresh whole prawns
5 cups water or chicken stock
2 stalks lemongrass, bruised & cut into long pieces
8 thick slices galangal
6 kaffir lime leaves, bruised & torn
3 Thai chillies, bruised
½ cup evaporated milk
150g oyster mushrooms
2 ½ Tbsp. น้ำพริกเผา Nam Prik Pao (Thai Chilli Paste)
2 – 3 limes, juiced
น้ำปลา Nam Pla (Thai Fish Sauce), to taste
1 First off, make a prawn stock by removing the heads, shells and veins from the prawns (reserve the peeled prawns for later) and frying in a pan with a little oil for a few minutes until the shells turn bright red and have slightly caramelised. Add a bit of water to deglaze the pan and then add the remaining water. Bring to a boil and then simmer on a low heat for 20 minutes. Optional step: In order to maximise the prawn flavour you can blitz the stock using a hand blender and then straining through a fine mesh. Alternatively, you can just fish (pun intended) out the prawn shells out of the stock. I’ve never seen a Thai recipe that actually blitzes it but this is my personal touch. 2 Once the prawn stock is ready bring back to gentle boil and add kaffir lime leaves, galangal, lemongrass and chillies and then simmer on a low heat for 10 minutes to infuse the aromatics in the stock. 3 Dilute the Nam Prik Pao with a few spoonfuls of stock and then add to the prawn stock along with the evaporated milk, 2 Tbsp. Nam Pla and oyster mushrooms. Cook for 1 – 2 minutes on medium heat. 4 Add the shelled prawns to the soup and cook for about 1 minute or until the prawns are cooked to your preference.
5 Turn the heat off and cool slightly (around a minute) and then add half the lime juice. If you add the lime juice in the boiling stock you’ll lose the freshness and perhaps curdle the milk so it’s best to wait a little bit before ruining your hard work.
6 Taste test: taste the soup and adjust lime juice and fish sauce according to your personal preference but keep in mind that it should be quite sour. 7 As with most Thai soups, serve with Thai Jasmine rice. If you’d rather go rogue and against Thai tradition just eat it on its own just like a western style soup; it’s your choice.