Ingredients

Equipment Needed

• •Charcoal grill, gas flame, or cast-iron pan for charring aromatics
• •Medium stockpot
• •Slotted spoon
• •Fine strainer for tamarind

Instructions

1. 1

   Roast the aromatics

   Place the unpeeled shallots, lemongrass pieces, and galangal slices directly on a charcoal grill, under a broiler, or in a dry cast-iron pan over high heat. Char them until the skins are blackened and blistered, turning occasionally. The shallots need about 8 minutes, turning every couple of minutes until soft inside and charred outside. Lemongrass and galangal need about 5 minutes, until fragrant and spotted black. The kitchen should smell smoky and sweet. This roasting step is what makes it tom khlong. Skip it and you've made a different soup entirely.

   If you have a gas stove, hold the shallots with tongs directly in the flame. That's how village cooks do it. Direct fire gives the best char. An oven broiler works if that's what you have, but get them as close to the element as possible.
2. 2

   Prepare the smoked fish

   If your smoked fish is very dry and stiff, grill or broil it briefly for 3 minutes per side to warm it through and reactivate the smoky aroma. Let it cool enough to handle, then flake the flesh off the bones into large chunks. Don't shred it fine. You want substantial pieces that hold their shape in the broth. Pick through carefully for bones. Reserve the head and bones for the stock. That's where the deepest flavor lives.

   Smoked catfish (pla duk yang) is the most traditional choice. Smoked snakehead (pla chon yang) is also excellent. Find these at Southeast Asian grocery stores, usually in the freezer section or hanging near the dried goods. The quality of the fish determines the quality of the soup. There's no way around it.
3. 3

   Build the broth

   Bring the water to a boil in a pot. Add the fish head and bones, the charred shallots (peeled now, outer burnt skin removed, the soft caramelized flesh inside is what you want), the charred lemongrass, and the charred galangal. Add the dry-roasted dried chilies. Let this simmer for 10 minutes. The broth will turn cloudy and golden, pulling smokiness from the fish and sweetness from the roasted aromatics. This is the foundation. Taste the broth at this point. It should already taste like something. If it's flat, your fish wasn't smoky enough or your aromatics weren't charred enough.

4. 4

   Add tamarind and season

   Pour the strained tamarind water into the broth. Add the fish sauce and padaek. Stir once. The broth will deepen in color, turning from golden to a murky amber-brown. That's correct. Add the palm sugar, just a pinch, enough to round the edges of the tamarind's sourness without making it sweet. Taste now. The balance should be: sour first and foremost, salty from the fish sauce and padaek backing it up, with the smokiness threading through everything. This is not the sharp bright sourness of tom yum. This is a deeper, slower sour. Adjust the tamarind if you need more acid. Adjust the padaek if you need more funk.

   Padaek is not the same as nam pla. Fish sauce is clear, refined, salty. Padaek is cloudy, thick, funky, with chunks of fermented fish. It delivers umami and a fermented depth that fish sauce alone cannot replicate. If you're cooking Isan food seriously, padaek is not optional. Find it at any Thai or Lao grocery. The jar will look murky and smell aggressive. That's how you know it's right.
5. 5

   Add mushrooms and fish

   Remove the fish head and bones from the broth with a slotted spoon. Add the torn oyster mushrooms and the grachai matchsticks. Simmer for 2 minutes until the mushrooms soften. Then add the flaked smoked fish pieces. Cook for just 1 minute more. The fish is already cooked. You're warming it through and letting it absorb the broth. Don't stir aggressively or the fish will break apart into nothing.

6. 6

   Finish with herbs

   Remove the pot from the heat. Add the bruised bird's eye chilies, torn kaffir lime leaves, sawtooth coriander, green onions, and fresh dill. Stir gently once. The herbs go in off the heat so they wilt but don't cook. They should still be bright and fragrant when the soup hits the bowl. Ladle into bowls, making sure each serving gets a good portion of fish, mushrooms, and herbs. Serve immediately with sticky rice (khao niew). Not jasmine rice. Sticky rice. That's the Isan way.

Chef Tips

• •Tom khlong and tom yum are not related dishes with minor differences. They're built on completely different systems. Tom yum uses raw aromatics infused in broth, with lime as the acid. Tom khlong uses roasted aromatics, with tamarind as the acid. The protein in tom yum is fresh. The protein in tom khlong is smoked. Understanding that these are different systems, not variations of the same dish, is how you start to understand Isan cooking on its own terms.
• •Tamarind sourness and lime sourness are not interchangeable. Tamarind (makham) gives a round, fruity, slightly sweet acidity that builds slowly. Lime gives a sharp, bright, immediate hit. Tom khlong requires tamarind. If you use lime, you've made a different soup. Ajarn always said: the acid defines the dish. Know your acids.
• •Sawtooth coriander (pak chi farang) and fresh dill (pak chi lao) are structural herbs in Isan cooking, not garnishes. Pak chi lao literally means 'Lao coriander,' which tells you exactly where this herb tradition comes from. If you can't find sawtooth coriander, regular cilantro is an acceptable substitute. Dill has no substitute. Find it or leave it out and acknowledge the gap.
• •The smoked fish quality determines everything. A good pla yang should smell deeply smoky, with firm flesh that flakes into substantial chunks. Avoid fish that's been dried to the point of being brittle and tasteless. If the fish doesn't smell like it's been near a fire, it won't do its job in the soup.

Advance Preparation

• •The aromatics can be charred up to a few hours ahead. Keep at room temperature.
• •Tamarind water can be prepared and strained a day ahead. Refrigerate.
• •The smoked fish can be flaked and bones separated ahead of time. Keep refrigerated.
• •Do not add the fresh herbs until the moment of serving. They lose their aroma and color within minutes of contact with hot broth.

Frequently Asked Questions

Nutrition Information

1 serving (about 450g)