Tom Som — Sour Tamarind Fish Soup / ต้มส้ม

Central Thai — a lighter, more restrained sour soup than the Southern gaeng som; considered a restorative and digestive preparation

Tom som is the Central Thai sour fish soup — lighter than gaeng som and without the Southern curry paste base, it is a clear, tamarind-acidic broth with ginger, shallots, and galangal as aromatics, and fresh fish (typically whole or in steaks) as the protein. The sourness comes primarily from tamarind water, with lime providing a brighter secondary acid. It is considered a digestive soup and is often served at the beginning of a multi-dish meal. The ginger component is more prominent here than in other Thai soups — it is added in julienned strips rather than as a paste component, contributing both flavour and a slight peppery heat.

Tom som's bright, clean acidity is a palate primer rather than a destination dish — its function at the beginning of a Thai meal is to prepare the mouth for the richer flavours that follow.