Pounding a curry paste

How to tell it is going right

• Smeared thin across a pale surface it reads as one substance, edge to edge: no pale gritty specks standing proud of the smear, no shard that drags a line through it as the smear is pulled. Flecks mean something hard went in after something wet and skated instead of shattering.
• Rubbed between finger and thumb it feels like wet clay, dense and smooth, and takes the print of the thumb. Anything that rolls into a hard grain or grits like sand has not been broken down, and the order of work was wrong.
• The fibrous aromatics have surrendered: pinch a little and pull, and nothing draws out as a thread or a hair. Listen to the last minutes of work as well, which should be a dull wet slap in the mortar; a dry knock or rattle still present means hard pieces are being chased around rather than crushed.
• One even colour throughout when it is turned under the light, deep and saturated, with no marbling and no streak in which a single component can still be read. A dull grey cast over the surface says it was worked long past its point.
• Heaped up and left alone it stands in a soft peak and holds the mark of the pestle for a full minute: no clear or coloured liquid creeps out at the base, no oily film separates on top. It should also come to the pass cool, no warmer than about 25 C (77 F); a mortar warm to the back of the hand means friction has driven off the top aroma and the paste will smell flat.

Where it goes wrong Everything went into the mortar together, or the wet ingredients arrived before the hard, dry ones had been reduced to dust, so the moisture cushioned every blow and the hard pieces slid rather than broke. What comes to the pass is a wet mince rather than a paste: hard flecks and fibrous threads through a loose slurry, liquid weeping out of the heap within a minute, colour marbled instead of single, and on the plate it reads as separate raw items sitting next to each other rather than one flavour.