Mortar and Pestle: Why Thai Cooks Still Pound by Hand

Walk past a Thai kitchen, or a papaya salad stall, and you will often hear it before you see it: the steady knock of a pestle against a mortar. In Thai the mortar is called krok and the pestle sak, and together they remain one of the most important tools in the kitchen, even in homes with a perfectly good blender.

This is not nostalgia. Pounding by hand produces a different result from chopping with a blade, and many Thai dishes depend on that difference.

Two kinds of mortar

Thai kitchens commonly use two quite different mortars, each suited to a different job.

• Granite mortar (krok hin). Heavy, deep and made of solid stone, with a stone pestle. It is used for grinding and pounding: curry pastes, chilli dips, spice mixtures and garlic. The weight does much of the work. The town of Ang Sila in Chonburi province, on the eastern Gulf coast, has long been known for its granite mortars.
• Clay or wooden mortar with a wooden pestle. Taller, lighter and with a narrower bowl. It is used for bruising and mixing rather than grinding, above all for som tam and other pounded salads. The softer wooden pestle crushes ingredients without breaking them into a paste.

If you buy only one, a good granite mortar with a bowl of around 15 to 20 centimetres across is the more versatile choice. For som tam you can manage by bruising gently in a granite mortar, though a clay or wooden one is easier.

Why pounding is different

A blender cuts ingredients into smaller and smaller pieces. A pestle crushes them. Crushing breaks open the cells of lemongrass, galangal, garlic and chillies and releases their oils and juices, so the paste becomes fragrant and cohesive, with ingredients bound together rather than sitting as tiny separate pieces.

Pounding also works without added liquid. A blender usually needs water or oil to turn the blades, which dilutes the paste and makes it harder to fry properly in coconut cream or oil. A hand-pounded curry paste is drier and more concentrated, and it releases its aroma more readily when it hits the pan.

Finally, pounding gives control. You can stop when garlic and chillies are roughly crushed for a dipping sauce, or keep going until a curry paste is completely smooth. Many chilli dips, such as nam prik noom, depend on that coarse, uneven texture.

How to pound a curry paste

The secret is order. Hard, fibrous and dry ingredients go in first, soft and wet ones last. If the wet ingredients go in early, everything slides around the bowl and the tough pieces never break down.

1. Toast and grind any whole dry spices, such as coriander and cumin seeds, first. Tip them out and set aside.
2. Pound soaked dried chillies with a pinch of salt. The salt acts as an abrasive and helps break them down.
3. Add the hardest aromatics, finely sliced: lemongrass, galangal, then makrut lime zest and coriander root. Slicing across the fibres first makes the work much easier.
4. Add the softer ingredients: shallots, garlic, and fresh turmeric or krachai if the recipe uses them.
5. Finish with shrimp paste and the ground spices, pounding until the paste is smooth and evenly coloured.

Use a firm, steady, vertical motion, letting the pestle drop rather than forcing it, and scrape down the sides with a spoon from time to time. Holding a cupped hand over the mouth of the mortar stops pieces of chilli flying out. A full curry paste takes a while, and it is normal to need a rest.

Som tam: bruising, not pounding

Som tam shows the other side of the mortar. Here the aim is not a paste but a salad in which everything is lightly crushed and coated in dressing. The Thai word tam means to pound, and the dish is sometimes nicknamed pok pok after the sound it makes.

1. Pound garlic and chillies briefly in the clay or wooden mortar until roughly crushed.
2. Add dried shrimp and peanuts if using, and crush lightly.
3. Add palm sugar, fish sauce and lime juice, and stir with the pestle until the sugar dissolves.
4. Add the shredded green papaya, tomato and long beans. Bruise them gently with the pestle while turning and lifting the salad with a spoon held in the other hand, so the dressing coats every strand.
5. Taste and adjust, then serve straight away.

Too much force turns the papaya watery and limp. The gentle bruising lets the dressing soak in while the strands stay crunchy.

Choosing and caring for a mortar

• Choose weight. A heavy granite mortar stays put on the counter and does the work for you. Light, thin ones tend to skid around.
• Look for a rough, unpolished inner surface. Very smooth mortars let ingredients slip rather than grip.
• Season a new granite mortar before first use by pounding a handful of uncooked rice to a powder, discarding it and repeating until the powder stays clean and white. This removes loose grit from the stone.
• Wash with hot water and a brush. Avoid soaking a wooden pestle or clay mortar, and dry them well.
• Stand the mortar on a folded cloth to protect the counter and quieten the noise.

When a blender is fine

None of this means a blender has no place in a Thai kitchen. Many Thai cooks use one for large batches of curry paste, and plenty of households simply buy ready-made paste from the market. A useful compromise is to pound the toughest aromatics such as lemongrass and galangal by hand, then finish the paste in a small food processor with as little liquid as possible.

For smaller jobs, though, a mortar is often quicker than getting out a machine, and it is much easier to clean. Crushing a few cloves of garlic with chillies for pad kra pao, or bruising herbs for a dipping sauce, takes less than a minute. Once you get used to the rhythm, it becomes one of the more satisfying parts of cooking Thai food at home.