Tom Yum Broth (Water to Lemongrass to Lime Base)

1 liter

Water or light chicken/prawn stock — Prawn shell stock deepens seafood tom yum; plain water is traditional for the clearest broth

3 stalks (approx. 120 g)

Lemongrass stalks (bruised, cut to 5 cm pieces) — Use the pale bottom third; bruise hard with a knife heel to open volatile oil cells

5 leaves

Kaffir lime leaves (torn) — Tear to break the midrib and release citrus-floral oils; do not chiffonade — coarser tearing infuses more slowly and evenly

4 slices (approx. 30 g)

Galangal (fresh, sliced 3–4 mm) — Not interchangeable with ginger; galangal provides pine-camphor-citrus notes that define tom yum

3–8, to taste

Bird's eye chillies (smashed) — Smash rather than slice to control heat release; more chillies added at end for intensity

3 tbsp per liter

Fish sauce (nam pla) — Tiparos or Megachef preferred; Sriracha-brand fish sauce is acceptable

2–3 tbsp per liter

Lime juice (fresh) — Added off heat to preserve bright acidity; bottled lime juice flattens the broth

Bruise lemongrass stalks aggressively with the flat of a knife, fold into 5 cm sections. Tear kaffir lime leaves through the midrib. Combine water or stock, lemongrass, galangal, kaffir lime leaves, and smashed chillies in a pot. Bring to a boil, reduce to a firm simmer, and infuse uncovered for 8–10 minutes. The broth should turn pale gold and smell intensely citrus-herbaceous. Add protein (prawns, mushrooms, tofu, chicken) and cook briefly. Season with fish sauce off heat. Add lime juice last, never on heat. Taste for the four-pillar balance: salty (fish sauce), sour (lime), hot (chilli), and the gentle background sweetness from the lemongrass itself. Adjust each independently.

• Bruise aromatics hard — gentle cutting releases fewer volatile oils. Slap lemongrass stalks on the cutting board before slicing.
• Add lime juice off heat: heat destroys the fresh volatile acids and turns lime juice flat and faintly bitter.
• Taste the four flavors independently: add fish sauce for salt, lime for sour, smashed chillies for heat. Sugar is a last resort — the lemongrass provides residual sweetness.
• Infusion time matters: under 5 minutes produces weak broth; over 15 minutes pushes galangal's piney notes into bitterness. The 8–10 minute window is non-negotiable.
• The aromatics are not meant to be eaten — bruise them large enough to be easily removed or push to the side of the bowl.
• For a deeper broth without coconut milk, dry-roast the galangal and shallots before infusing — this is common in Isaan (northeastern Thai) versions.

• Tom Yum Goong (prawn tom yum)

  Build broth with prawn heads and shells first; strain before adding the aromatics for a layered seafood depth

• Tom Yum Gai (chicken)

  Use bone-in chicken pieces simmered in the aromatic broth; cook time extends to 20–25 min for tenderness

• Tom Yum Nam Khon (creamy)

  Finish with 3–4 tbsp evaporated milk or light coconut milk per liter; rounds the acidity and softens heat

• Tom Kha Gai

  Cousin preparation: galangal and lemongrass infusion in coconut milk (not water), much lower chilli load, no lime juice in the broth itself

• Tom Yum Talay (seafood medley)

  Prawn shell stock base; mixed prawn, squid, and mussels added in order of cooking time — squid last to avoid rubberiness

• Brine (Salt to Water Percentage)

  Fish sauce in tom yum functions as a liquid seasoning brine; the 3 tbsp per liter norm is approximately 1.5% salt

• Miso Soup (Dashi to Miso)

  Structural parallel: a light aromatic broth seasoned at the end with a fermented liquid condiment, never boiled after seasoning

• Court Bouillon (Water to Wine to Vegetable Aromatics)

  Western analogue: aromatic poaching liquor built on infusion of vegetables and acid; compare infusion-to-seasoning logic

1. 1.Thai Food — David Thompson (Pavilion, 2002)
2. 2.Simple Thai Food — Leela Punyaratabandhu
3. 3.The Complete Asian Cookbook — Charmaine Solomon
4. 4.On Food and Cooking — Harold McGee (volatile oil extraction from bruising aromatics)

Confidence: high