Tom Saap (ต้มแซ่บ)

The Boiled Cousin of Tom Yum

ต้มแซ่บ translates plainly: "boil" + "deliciously spicy". It is the Isaan bowl you order next to your som tam — a clear, sour, chilli-hot soup built on pork bones instead of prawns, lime or tamarind instead of cream, and toasted rice powder instead of anything soft. Where tom yum gets coconut milk and a polite heat, tom saap gets ข้าวคั่ว — toasted rice — and a chilli count the sources measure in multiples of ten.

It belongs to the same family as tom yum — the galangal, lemongrass and kaffir lime are all here — but it is the country version: no coconut, bones to gnaw on, and a finish of roasted chilli and lime that hits the back of the throat. One Kapook roundup of six tom saap recipes has been read 1.9 million times, and the street-stall version on TrueID promises "ซดน้ำเกลี้ยงหม้อ" — drink the pot dry.

The bones matter. Sources cook it with กระดูกอ่อนหมู — pork spare ribs with their soft cartilage — an hour in the pot, then the broth is seasoned at the end, never boiled with the lime. Lime goes in after the fire is off; boil lime juice and it turns bitter, and every published version knows it.

The Recipe (serves 2–4 — the Kapook version, 1.9M reads)

The Method

1. Boil the bones. Ribs into the water, skim the scum until the broth runs clean — about an hour, until the bones are tender. (The street-stall version first boils the bones once and throws that water away; the home versions just skim.)
2. Wake the herbs. Galangal, lemongrass and kaffir lime leaves in; boil until the steam smells of them. A few minutes is enough.
3. Vegetables. Straw mushrooms, cherry tomatoes and shallot; simmer until just cooked through.
4. Season the broth. Fish sauce, tamarind water and sugar — taste, adjust, then kill the heat.
5. Finish off the fire. Lime juice, roasted chilli powder and toasted rice powder stirred in last, in the bowl or the pot. Serve hot with the herbs floating, sticky rice on the side.

Where Thai Sources Disagree

How Western Versions Get It Wrong

• Calling it tom yum. No coconut milk, no prawns, no galangal-broth forgiveness. Tom saap is pork and sour — a different dish.
• Boiling the lime. Lime juice cooked in the broth turns bitter and flat. Every Thai source adds it after the heat is off.
• Skipping the toasted rice. ข้าวคั่ว is what makes it Isaan — nutty, toasty, thickening the broth a touch. Plain rice flour is not the same.
• Boneless pork. The bones are the dish — you gnaw them. Fillet is for a different soup.
• A timid chilli count. One Pantip version calls for twenty bird's-eye chillies. "Deliciously spicy" is in the name.

UK Ingredient Notes

• Pork spare ribs with soft cartilage: butchers sell them as spare ribs; ask for the soft-bone cut (the same you'd use for Thai tom yam ribs).
• Galangal, lemongrass, kaffir lime leaves: fresh at Thai or East Asian grocers; galangal frozen in slices is a fair stand-in — ginger is not.
• Toasted rice powder: dry-toast raw sticky rice in a pan until golden, pound it — or buy ข้าวคั่ว at Thai grocers.
• Straw mushrooms: tinned at Thai grocers if fresh ones aren't around; oyster mushrooms substitute.
• Serve with sticky rice or jasmine rice — the Isaan pairing it's built for, next to som tam if you want the full table.

Sources

This recipe is translated from the following Thai-language sources. Where they disagree, we've said so.