Spicy Pork Spine Soup (Leng Saeb)

Ingredients

Equipment Needed

• •Large stockpot (at least 4 liters)
• •Fine mesh strainer for padaek
• •Dry wok or pan for toasting rice and chilies
• •Granite mortar and pestle (krok hin) or spice grinder for khao khua

Instructions

1. 1

   Blanch the bones

   Put the pork spine segments in a large pot, cover with cold water, and bring to a rolling boil. Let it boil hard for 3 minutes. You'll see scum, blood, and impurities rising to the surface. That's good. That's what you're getting rid of. Drain the bones, rinse them under cold running water, and scrub off any clinging residue. This step is non-negotiable. Skip it and your broth will be murky, cloudy, and taste like iron. Clean bones make clean broth.

   Ask your butcher to cut the spine into segments with a band saw. Trying to hack through vertebrae at home with a cleaver is a fight you don't need. Each piece should be about 3 inches long, exposing the marrow cavity on both ends.
2. 2

   Simmer the spine

   Return the cleaned bones to the pot with 2 liters of fresh water. Add the halved shallots. Bring to a boil, then drop to a low simmer. You want gentle bubbles, not a rolling boil. A hard boil emulsifies the fat into the broth and makes it greasy. A gentle simmer keeps the broth clear and lets the collagen dissolve slowly. Simmer for 1 hour to 1 hour 15 minutes. The meat should be pulling away from the vertebrae but still attached. You want to gnaw it off, not have it fall apart into the broth.

3. 3

   Toast the rice powder

   While the bones simmer, make the khao khua. Take 3 tablespoons of raw sticky rice (or jasmine rice if that's what you have) and toast it in a dry wok or pan over medium heat. Shake the pan constantly. The rice will go from white to golden to deep tan in about 5 minutes. Pull it off the heat when it smells nutty and looks like dark sand. Let it cool. Pound it in a mortar or grind in a spice grinder to a coarse powder. Coarse, not fine. You want grit, not flour. The texture is part of the dish.

   Khao khua is the same toasted rice powder used in larb. If you already have some, use it. But fresh-toasted always tastes better. The smokiness fades after a day or two.
4. 4

   Toast the dried chilies

   In the same dry pan, toast the dried bird's eye chilies over medium heat for 1 to 2 minutes, shaking constantly. They'll darken slightly and start to smoke. The smell should be sharp and smoky, not burnt. Pull them off and crumble them roughly between your fingers. Some vendors pound them lightly in a mortar. Either works. You want flakes and seeds, not powder.

5. 5

   Build the hot-sour broth

   When the bones are tender, add the bruised lemongrass, galangal slices, torn kaffir lime leaves, and bruised fresh chilies to the pot. Let them infuse in the simmering broth for 5 minutes. The aroma should shift from plain pork broth to something herbal, sharp, and alive. Now add the padaek and fish sauce. Stir. The padaek is the backbone here. It adds a deep, funky salinity that fish sauce alone cannot replicate. Fish sauce is a supporting player in this dish, not the lead.

   Strain the padaek liquid through a fine mesh sieve before adding. You want the flavor, not the fish chunks and bones floating in your broth. Unless you're in Isan and that's how your family does it. Then leave everything in. No judgment.
6. 6

   Season and finish

   Remove the pot from heat. Add the lime juice, sugar, toasted chili flakes, and khao khua. Stir once. Taste. Here's where you find the dish. The broth should hit you in this order: sour punches first, salt and funk from the padaek second, heat building in the background from the chilies, with the khao khua giving everything a smoky, grainy depth. If it's not sour enough, add more lime. If it's not hot enough, add more chili. The sugar is there to round the edges, not to sweeten. You should barely notice it. Ajarn always said: "Add sour last, add sour slowly." That applies double here because lime is the dominant note and there's no pulling it back.

7. 7

   Serve with sticky rice

   Ladle the bones into deep bowls, making sure everyone gets 3 or 4 big spine segments. Pour the broth over the top. Scatter the sawtooth coriander, spring onions, and cilantro over the surface. Serve immediately with sticky rice (khao niew). Not jasmine rice. Sticky rice. You tear off a piece of sticky rice, use it to pinch some meat from the bone, dip it in the broth, and eat. Between bites, pick up the bones with your hands and work them. Gnaw the meat. Crack the cartilage. Tilt the bone and suck out the marrow. That fatty richness against the searing broth is the whole experience. Have napkins ready. Your hands will be a mess. That's how you know you're doing it right.

Chef Tips

• •Padaek is not fish sauce. Do not substitute one for the other and think you've made the same dish. Padaek (ปลาแดก) is a chunky, unfiltered fermented freshwater fish preparation with a deeper funk, more complexity, and a completely different salinity profile than nam pla. Fish sauce is refined and clean. Padaek is raw and primal. Isan cooking is built on padaek the way Central Thai cooking is built on nam pla. If you can't find padaek, use pla ra (ปลาร้า) from a Thai grocery. As a last resort, use fish sauce with a small spoonful of shrimp paste (kapi) stirred in for depth. But know that you're approximating.
• •The bones are not decoration. Leng saeb is a bone-eating soup. The pork spine has meat clinging to the vertebrae, cartilage between the joints, and marrow in the cavities. Each component gives you a different texture and richness. If you're serving this to people who won't touch bones, make a different soup. This one requires hands.
• •Khao khua does double duty: flavor and body. Toasted rice powder adds a smoky, nutty grain flavor and thickens the broth just enough to give it weight without making it heavy. Add it off the heat so it doesn't clump. And grind it coarse. If it's fine like flour, you lose the texture that makes it matter.
• •Sticky rice (khao niew) is the only correct accompaniment. Every Isan soup, curry, and salad is eaten with sticky rice. Jasmine rice is Central Thai. Serving leng saeb with jasmine rice is like serving French onion soup with a tortilla. It works mechanically. It misses the point entirely.

Advance Preparation

• •The bones can be blanched and rinsed up to a day ahead. Store them covered in the refrigerator. This actually helps because cold bones release collagen more gradually when you start the simmer.
• •Khao khua can be toasted and ground a day or two ahead. Store in an airtight container. Freshly toasted is always better, but a day old is fine.
• •Do not add the lime juice, herbs, or khao khua until you're ready to serve. The lime loses brightness within minutes, the herbs wilt, and the rice powder gets soggy. Build the base broth ahead if you want. Season and finish at the last moment.

Frequently Asked Questions

Nutrition Information

1 serving (about 500g)