A sharp, clear, sour-hot broth-style curry — without coconut milk — of fresh turmeric, dried chillies, and shrimp paste as the paste base, acidified with tamarind or sour fruit (green mango, gooseberry) and seasoned with fish sauce. Gaeng som demonstrates the range of the Thai curry tradition: not all Thai curries are coconut-milk-based. The gaeng som is clear, bright, and acidic — a preparation for fish and vegetables where the sharpness of the souring agent is the primary flavour and the paste provides heat and aromatic depth without richness.
**The gaeng som paste:** - Fresh turmeric: peeled, sliced — not dried turmeric powder. Fresh turmeric provides a completely different aromatic profile: slightly earthy, slightly medicinal, with a freshness entirely absent from the dried powder. - Dried chillies: for heat. - Shrimp paste: for fermented depth. - Garlic and shallots. - White peppercorns. All pounded to a paste (Entry TH-01) — a simpler paste than the curry pastes, with fewer aromatic components. **The preparation:** 1. Bring fish stock or water to a boil. 2. Add the pounded gaeng som paste — directly to boiling water, not via cracking (there is no coconut cream in this curry to crack). 3. Add the souring agent: tamarind water (Entry TH-18) or fresh sour fruit. 4. Season with fish sauce. 5. Add fish (firm white fish, in large pieces) or prawns. 6. Adjust the four-flavour balance — gaeng som's balance is more sour-forward than most Thai curries. 7. Add vegetables: green beans, white cabbage, or any vegetable that benefits from a brief braise in a sour broth. Decisive moment: The sourness calibration. Gaeng som is named for its sourness — it should taste sharply, clearly, brightly sour before any other register. The sour is the lead; the heat follows; the salt provides the foundation. If the sourness is insufficient, the preparation is not gaeng som.
David Thompson, *Thai Food* (2002); *Thai Street Food* (2010)