Thailand's most famous soup — hot, sour, fragrant, and the first thing most visitors try.
A clear or coconut-cream broth spiked with lemongrass, galangal, kaffir lime leaves, fish sauce, and lime — shrimp (kung) is the classic protein.
Tom Yum Goong (with shrimp) is the standard; Tom Kha Gai adds coconut milk and chicken for a creamier, milder version.
Every Thai restaurant has it; street stalls usually excellent; upscale versions have better prawns; quality gap between good and bad is enormous.
Tom Yum is meant to be spicy — if you want mild, say 'mai pet'; the spice and sour together is the point.
