Tom Yum Paste (Kreung Tom Yum)

Ingredients

Equipment Needed

• •Heavy granite mortar and pestle (krok hin), at least 7 inches diameter
• •Small saucepan or wok for frying the paste
• •Clean glass jar with tight-fitting lid for storage

Instructions

1. 1

   Prepare the dried chilies

   Soak the dried red chilies in warm water for 15 minutes until they're soft and pliable. Drain, shake off excess water, and tear them open to remove most of the seeds. Keep a few seeds if you want more heat. The dried chilies give the paste its deep, smoky backbone and its reddish color. Fresh chilies alone won't do that. You need both.

   Use prik jinda haeng or prik chi fa haeng (medium-large dried Thai chilies). They have better color and smokiness than the tiny dried bird's eye. The fresh prik khi nu handles the sharp heat. The dried ones handle depth.
2. 2

   Pound the salt and chilies

   Start with the salt in the bottom of a heavy granite mortar (krok hin). The salt is your abrasive. It grips the ingredients against the stone and helps break them down. Add the drained dried chilies and the fresh bird's eye chilies. Pound firmly until you have a rough, fibrous paste. The chilies won't go smooth, and that's fine. You want them broken down enough to release their oils and pigment. The mortar should already smell sharp and hot.

   Granite mortar only for this paste. Not clay. The krok hin gives you the weight and the rough interior surface to break down fibrous ingredients like lemongrass and galangal. A clay mortar (krok din) is for som tam, where you're bruising, not pulverizing.
3. 3

   Pound the garlic and shallots

   Add the garlic and shallots to the mortar. Pound until they break down into the chili paste and everything starts to look wet and integrated. The garlic should be completely crushed, the shallots reduced to a fibrous pulp. These are the aromatic base of almost every kreung tam in the Thai system. They don't just add flavor. They create the body of the paste, the structure that holds everything together.

4. 4

   Pound the tough aromatics

   Add the sliced lemongrass first. Pound hard. Lemongrass is fibrous and stubborn. It fights back. Keep pounding until the fibers break and the paste turns fragrant and slightly wet with released oils. Your kitchen should smell like a Thai pharmacy right now: sharp, citrusy, herbal. Then add the chopped galangal. More pounding. Galangal is even tougher than lemongrass. It's dense and woody. Slice it thin before it goes in, or you'll be pounding all day. Then the cilantro roots. They break down faster, earthy and green, the anchoring note that ties the high aromatics to something grounded.

   Ajarn always said: slice fibrous ingredients thin before they go into the mortar. The mortar pounds, it doesn't cut. If you throw in a thick chunk of galangal, you'll be there for an hour and your paste will still have chunks. Thin slices. Then pound.
5. 5

   Add the kaffir lime

   Add the finely sliced kaffir lime leaves and the kaffir lime zest. Pound just until incorporated. This is the volatile layer. The citrus oils in makrut zest evaporate fast under heat and friction, so it goes in late and it gets pounded briefly. You want those oils trapped in the paste, not lost to the air. The aroma shift should be immediate: the paste goes from earthy-hot to bright-citrus-hot. That's the makrut doing its job.

6. 6

   Finish with shrimp paste

   Add the shrimp paste (kapi) last. Pound it in until the paste is uniform in color and texture. Kapi is the umami depth charge. It's wet, so it binds everything together and gives the paste its final consistency. The finished kreung tom yum should be rough but cohesive, fragrant enough to make your eyes water slightly, reddish-brown with visible flecks of chili and lemongrass fiber. Taste a tiny bit on your fingertip. It should be intensely aromatic, salty from the kapi, and hot. If it doesn't hit you in the back of the throat, you need more chili.

   Good kapi smells strong but clean, like the ocean concentrated. Bad kapi smells rotten. If your shrimp paste makes you recoil, it's either poor quality or too old. Find a Thai brand like Pantai or Tra Chang. Kapi is not optional. It's the difference between a paste and a pile of pounded herbs.
7. 7

   Fry the paste

   Heat the vegetable oil in a small saucepan or wok over medium heat. Add the entire paste and fry, stirring constantly, for 5 to 7 minutes. The paste will sizzle and sputter. The color will deepen. The aroma will shift from raw and sharp to rounded and complex. You'll know it's done when the oil starts to separate and pool at the edges of the paste, and the raw shrimp paste smell disappears completely. That oil separation is the signal. It means the moisture has cooked out and the paste is ready for storage.

   Frying the paste does two things: it blooms the essential oils (making them more aromatic) and it drives out moisture (making the paste shelf-stable longer). An uncooked paste will keep for a week refrigerated. A fried paste keeps for a month, easily.
8. 8

   Cool and store

   Let the paste cool completely in the pan. Transfer to a clean glass jar with a tight lid. Press it down to eliminate air pockets. Pour a thin layer of oil over the top to seal it. Refrigerate. It keeps for a month. To use: two tablespoons of paste in four cups of hot water, add your protein and mushrooms, finish with nam pla, nam manao, and nam tan pip. Tom yum in ten minutes. The kreung tam did the work for you.

Chef Tips

• •The order ingredients enter the mortar is not random. Hardest and most fibrous first (dried chilies, lemongrass, galangal), aromatics that break down easily in the middle (garlic, shallots, cilantro root), volatile and delicate ingredients near the end (kaffir lime zest and leaves), and wet binders last (kapi). This order is physics: you can't pound lemongrass into a paste that's already wet with shrimp paste. The fiber just slides around. Dry pounds dry. Wet finishes.
• •Cilantro roots (rak pak chi) are not cilantro stems. The root is a distinct ingredient with an earthy, concentrated flavor that anchors the brighter aromatics. Thai markets sell cilantro with roots attached. If your cilantro has no roots, you're buying the wrong cilantro. In a pinch, use the lower stems, but know you're getting maybe 30% of the flavor.
• •This paste builds the following dishes: tom yum goong (shrimp), tom yum gai (chicken), tom yum pla (fish), tom yum het (mushroom), tom yum talay (mixed seafood). It also works as a stir-fry base, a fried rice seasoning paste, or a marinade for grilled proteins. Two tablespoons in hot broth is the standard ratio. Adjust from there.
• •Don't confuse this with nam prik pao (roasted chili jam). Nam prik pao is a separate condiment added to tom yum at the end for smokiness and color. This kreung tom yum is the aromatic foundation. The two work together in the finished soup but they're different preparations with different jobs. The paste builds the broth. The nam prik pao finishes it.

Advance Preparation

• •Fried paste keeps for 1 month refrigerated in a sealed glass jar with a thin oil layer on top. It also freezes well for up to 3 months: portion into ice cube trays, freeze solid, then transfer to a zip-lock bag. Each cube is roughly one serving.
• •Raw (unfried) paste keeps for about 1 week refrigerated. Frying extends shelf life significantly by driving out moisture and blooming the oils.
• •To use: drop 2 tablespoons of paste into 4 cups of simmering water or stock. Add protein (shrimp, chicken, mushrooms). Finish off heat with fish sauce (nam pla), lime juice (nam manao), a pinch of palm sugar (nam tan pip), and optionally a spoonful of nam prik pao. Tom yum in ten minutes.

Frequently Asked Questions

Nutrition Information

1 serving (about 40g)