Pestle and mortar

Why pounding is different

A food processor blade slices repeatedly at high speed. It reduces things to small pieces, and it does so fast enough to generate heat, which drives off volatile aroma compounds — and for herbs it bruises and oxidises the cut surfaces.

A pestle crushes and smears. Cell walls rupture and their contents are pressed into the surrounding mixture rather than remaining as separate fragments. The result is a genuine emulsion of oils, water and solids rather than a suspension of small pieces.

Whether that matters depends on what you are making. For pesto, a spice paste, a garlic and salt paste, or anything where the point is that everything has merged, it matters a great deal. For chopping an onion, it does not.

Which material

Granite

Heavy, rough interior, grips and grinds well. The best all-round choice and the one to buy if you buy one.

Marble

Handsome, smooth, and the smoothness makes it slippery and less effective. Better for soft mixtures than for spices.

Ceramic

Light, glazed, easy to clean, and only moderately effective. Fine for small quantities of spice.

Wood

Traditional in South East Asia for soft pastes. Absorbs flavour and cannot handle hard spices.

Volcanic stone (molcajete)

Very rough and very effective, and it needs seasoning before first use.

Size

Bigger than you think. A small mortar throws its contents out. Aim for at least 15cm across.

What it is best for

• Whole spices, especially after toasting. The flavour difference against pre-ground is substantial.
• Garlic and salt paste. Salt acts as an abrasive and the result is a smooth paste no blade produces.
• Pesto and herb pastes. Traditional and genuinely better — less bruised, less bitter, better emulsified.
• Curry pastes and spice blends. Where the ingredients need to merge rather than sit alongside each other.
• Crushing rather than grinding — coriander seed cracked coarsely, peppercorns roughly broken, juniper opened.
• Small quantities, where a processor cannot reach the food at all.

Using one

1. Work in small batches. Overfilling means nothing gets crushed.
2. Start by cracking, not grinding — press down and break things open before you begin the circular motion.
3. Add a pinch of coarse salt when grinding soft things like garlic or herbs. It provides abrasion and does most of the work.
4. Use a firm circular grinding motion with the pestle angled, pressing outwards against the wall rather than straight down.
5. Add ingredients in order of hardness — hardest first, softest last, liquids at the very end.
6. Clean it with hot water and a brush, and no detergent for porous stone, which absorbs it. Grind a little rice to clean and deodorise.

Common questions