Thin, soft, slightly sour round rice noodles produced by a traditional fermentation process — the rice is soaked, fermented for 2–3 days, then ground wet, the batter allowed to ferment further, cooked by forcing through a sieve into boiling water, and the resulting noodles arranged in small nest portions. Khanom jeen is the base for khanom jeen nam ya (Entry TH-44) and khanom jeen nam phrik — the noodles served with various warm sauces poured over them. The slight sourness of the fermented rice noodle is not a defect but a specific quality that matches the richness of the sauces served with them.
**Why fermentation matters:** The 2–3 day fermentation of the soaked rice before grinding produces lactic acid bacteria activity — the same fermentation as sourdough bread. This lactic acid activity provides the slight tanginess of the noodle and breaks down some of the starch, making the cooked noodle more digestible and with a slightly more complex flavour than unfermented rice noodles. **Commercial khanom jeen:** Fresh khanom jeen is available from Asian grocery stores in Thai communities. Refrigerated, it keeps for 3–4 days. The slight sour note should be present but not overwhelming — a fresh, clean tang rather than an aggressive sourness. **The serving format:** Unlike most Thai noodle preparations, khanom jeen is served at room temperature — the noodle nests laid in a bowl, the warm sauce poured over at service. The temperature contrast (warm sauce, room-temperature noodles) is part of the dish's character. **Accompaniments:** The vegetable, herb, and raw accompaniment plate is as important as the noodle and sauce — fresh bean sprouts, cucumber, wing beans, Thai sweet basil, kaffir lime leaf, hard-boiled eggs. These raw accompaniments provide both textural contrast and freshness against the richness of the poured sauce.
David Thompson, *Thai Food* (2002); *Thai Street Food* (2010)