Fish and tomato soup with kaffir lime, cilantro, prickly ash (gaeng som pla makan) serves 2-4 depending on demeanour, girth and appetite.
Forget the complexities of Tom Yum and Tom kha – they are done to death and you’ll never make your critics happy.
The newbies will love it – but everybody else has their own favourite taste memory. Each has a thousand different incarnations depending on background, cook and diner preference. Plus – it’s so common everywhere, it won’t be a ‘first impression’
Apologies to accomplished Thai chefs: This doesn’t apply to you. Your tom yum is probably mouthwatering. But add this to your repertoire and watch us silly Farangs start drooling and kowtowing.

In the culinary world, simplicity and freshness aces complexity. As easy as that. (Those words will come back to haunt me because of my frog recipe, I’m sure)
This catfish soup has everything.
Incredible taste, fresh local ingredients, and such simplicity that it is almost fool-proof. I have to say that this soup has taken over my “favourite” status from the roasted chilli and kaffir lime “Tom Saap” pork rib soup that I wrote about last year.

First – get a fish.
Here in North Thailand we are using catfish or similar freshwater fish.
In the South they would rather eat bony sea sprats from the ocean than plump tasty river fish. It’s a fresh locally available food thing. What they are used to. You try it too! get a fresh local fish from where you live, not a frozen one or an import. ”Your favourite fish” can be inserted without incident.
Do NOT drive all over town to the Asian shops looking for a place that has north Thai catfish
You will also need “Ma-kwem” – or prickly ash berries. <cue sad disappointed stare>
Fortunately, Robyn from the eatingasia blog wrote me to say that this can be substituted with Sichuan pepper and a little grated orange peel (No white pith from the orange though – it is bitter!)
Here is the recipe. Serve with rice, or sticky rice – or just a spoon and bib.

Ingredients:

• 500g / 1 each Freshwater catfish (or your favourite whole fish)
• 1-2 Tomato – ripe, red.
• 100g / 1 ea Onion (or red shallots if you can get them)
• 30g / 6 cloves Garlic
• 15g / 6 ea Chilli, fresh, red Thai (to taste)
• 800ml / 3-4 cups Water
• Salt, Sugar, optional MSG if you like it. (Sugar, salt to taste. Everyone’s is different, so balance these flavours yourself) As a rule – salt to taste, and just put a hint of sugar.
• 1 tsp Dried prickly ash berry – ground (or can substitute with Sichuan pepper pounded with a little orange zest if you cannot get prickly ash)
• 10-12 leaves long cilantro (sawtooth / flat coriander) – or fresh coriander
• 4 each Spring onion
• 2 each Kaffir lime – juice. (you can substitute lime juice & lime leaf)

1. Cut the fish roughly into large chunks. It is best cooked on the bone to flavour the soup. If you have roe – use that too – but don’t chop.
   A workaround, (to avoid picking at bones when you eat it) is to fillet the fish, pinbone it, then make a stock by simmering the bones very gently in water for 10-12 minutes only. DON’T BOIL.
   Then use the stock instead of water in step 5
2. Chop the 3/4 of the garlic and all the chilli. Pound it in a mortar and pestle. OR just chop it a bit more.
3. Slice the onion (with the grain – not into rings)
4. Cut the tomato as you wish. Wedges or julienne both work fine. Cut the core out though, and don’t use it
5. Bring the water to a gentle simmer in a pot.
6. Add in the chilli and garlic
7. Add the fish.
8. Reduce to a gentle simmer. Cook gently until the fish is just cooked through (5-10 minutes) DON’T BOIL!
9. Season soup with the salt. Taste it. Add a little sugar – this will deepen the flavour
10. Pound / grind the prickly ash with the remaining 1/4 of garlic that you kept from earlier.
11. Remove from heat, add in the prickly ash / Sichuan pepper, squeeze the kaffir limes in and tear some cilantro leaves into the soup
12. Serve immediately and bliss out. Every spoonful is good for you – but tastes good enough to be a mortal sin.
    The flavour and ‘awesomeness’ comes from the prickly ash or “ma-kwem”/ “Ma-kan”. Get some!
    Make sure you add the Schezuan pepper & orange skin if you don’t have it, or you just get a boiled fish soup.

Make it a gentle simmer. No – scratch that – Make it an almost IMPERCEPTIBLE simmer. Boiling destroys fish. And eggs. And chicken. And it toughens meat. Boiling should only be used for politicians and naughty children that scream loudly in trains all the way from Sydney to Gosford.