Green curry (gaeng khiew wan — literally 'sweet green curry') is central Thai in origin, and its combination of fresh chilli heat with coconut milk sweetness is the balance for which the preparation is named. Thompson notes that the 'sweet' in the name does not refer to an added sweetness but to the quality of the colour — a term of aesthetic appreciation for the vivid green of the fresh chilli paste.
The green of this paste is not from vegetables — it is from fresh chillies, specifically the small, intensely hot green bird's eye chilli (prik kee nuu) and the longer, milder green spur chilli (prik chee fa). Green curry paste is the hottest of the common Thai curry pastes, not the mildest — the fresh chillies provide a heat that is sharper, more immediate, and more penetrating than the mellower warmth of dried chillies in red paste. It is also the most aromatically fresh: the volatile citral of lemongrass and the bright, sharp note of kaffir lime zest are more pronounced in a green paste because the fresh chillies do not provide the smoky, dried depth that moderates the top aromatics in red.
As Segnit notes, lemongrass and coconut milk is among the most extensively documented of all tropical flavour pairings — the lemongrass's citral (specifically geranial and neral, the two forms of citral) dissolves into coconut fat with exceptional efficiency and is released thermally during cooking, producing the signature fresh-citrus top note of green curry. Green chilli's chlorogenic acids (the source of its fresh, slightly green, vegetal heat) complement the lemongrass citral in a way that red chilli's capsaicin-dominant heat profile does not — the green curry's heat is literally different in chemistry from the red, not merely in intensity.
**Thompson's green curry paste components:** - Small green bird's eye chillies (prik kee nuu): 15–20 fresh, for heat. - Long green spur chillies (prik chee fa): 5–8 fresh, for colour and moderate heat. - Fine sea salt: 1 teaspoon. - Lemongrass: 3 stalks, white part, sliced. - Galangal: 2cm piece, peeled, sliced. - Kaffir lime zest: from 1 kaffir lime. - Coriander root: 4–5 roots. - White peppercorns: 1 teaspoon. - Coriander seed: 1 teaspoon, toasted, ground. - Cumin: ½ teaspoon, toasted, ground. - Garlic: 6 cloves. - Shallots: 4 medium. - Shrimp paste: 1 tablespoon. [VERIFY] Thompson's exact proportions from the source text. **The green paste pounding difference:** Fresh chillies contain significantly more water than dried. They must be pounded first and reduced to a near-dry fibrous mass before the other aromatics are added — if the lemongrass is added to an underpounded wet chilli paste, the moisture prevents the lemongrass fibres from being effectively reduced. Pound the fresh chillies alone with the salt until they are nearly dry and the salt has absorbed most of the moisture — 5–8 minutes of vigorous pounding — before any other ingredient is added. **Preserving the green colour:** Green curry paste oxidises and turns a dull brown-green within hours of pounding. For maximum colour impact: pound at the last possible moment before cooking, or add a small amount of kaffir lime leaf or fresh coriander leaf to the paste immediately before cooking (not before pounding — the leaf's colour degrades more slowly than the paste's chlorophyll). Commercial green curry paste is always dull olive-coloured precisely because of this oxidation. Decisive moment: The moment the fresh chillies have been reduced to a near-dry, fibrous paste before any other ingredient is added. This stage — unique to green curry paste and not required with dried chillies in red — is the preparation step that makes the difference between a green paste of integrated depth and one where the chilli moisture prevents the aromatic fibres from being effectively pounded. The salt draws the moisture from the fresh chilli cells (osmosis) during the initial pounding — salt first with fresh chillies is the rule. Sensory tests: **Sight — colour of the finished paste:** Vivid, deep green — from the chlorophyll of the fresh chilli flesh. Hold the paste against a white surface: it should be genuinely, vividly green. Immediately after pounding: bright. After 30 minutes: beginning to dull. After 2 hours: significantly browned. This is the oxidation timeline. Freshly pounded = vivid; commercial = olive. **Smell — the fresh character:** Green curry paste smells more immediately fresh and citrus-bright than red — the fresh chilli's clean vegetal heat, the lemongrass citral, and the kaffir lime zest's limonene create an aromatic profile that is distinctly lighter and more volatile than the smoky depth of red. This brightness is the preparation's defining character — it should be present from the moment the wok lid is removed at service.
- Thompson's green curry uses chicken or fish — the fresh, volatile aromatic profile of the paste pairs with lighter proteins better than with the richer beef or lamb that absorbs the deeper red paste - A few kaffir lime leaves torn and added to the curry along with the thin coconut milk re-amplifies the limonene that was present in the paste's kaffir lime zest — reinforcing the brightness through the entire dish - Thai green curry uses small Thai eggplants (makeua phuang) and pea eggplants (makeua phiang) — not the large purple eggplant. The small white eggplants provide a slightly bitter, firm bite against the richness of the coconut; the pea eggplants pop in the mouth and release a brief bitterness.
— **Dull olive-brown paste lacking vivid green:** Oxidation — the paste was pounded too far in advance. For vivid green presentation: pound the paste as close to cooking as practical. — **Watery paste that lacks cohesion:** Fresh chillies not reduced sufficiently before other ingredients added. The moisture from the fresh chilli should be largely eliminated in the first pounding stage.
David Thompson, *Thai Food* (2002); *Thai Street Food* (2010)