Scoring

How to tell it is going right

• Lift one cut open with a fingertip: it parts through the skin and stops in the fat beneath, showing a pale wall at its base. Any cut showing red or fibrous flesh has gone too deep; any that has not reached the fat has left the skin tethered, and it will tighten under heat.
• The lines run parallel at even spacing, roughly a finger's width apart, each carried the full length of the face and stopped the same margin short of the edge. Sight down them: lines that converge, wander or crowd at one end cook at different rates and read as careless on the plate.
• Each line is one clean draw of the blade held at a slant, not a sawn or doubled track, and it leaves a bevelled lip standing slightly proud rather than a vertical slot. The surface should be dry and cold, near 4C (39F), when it is cut; worked warm and slack it drags, and the blade tears where it should part.
• After cooking the cuts have opened and set, each a clear gap with firm browned walls. Lines closed back to faint scratches were cut too shallow or too straight down, and the surface has shrunk over them instead of through them.
• The piece lies flat and true when it is set down, with no cupping through the middle and no lifted, curled edge. A bowed piece means the tightening surface was never released, so it pulled the whole thing up and left the underside pale where it stood off the heat.

Where it goes wrong The blade was pushed rather than drawn, through a surface left warm and slack, so it went past the fat and into the flesh. The cuts bleed as they cook and the juices flood the surface, so it steams instead of crisping: the lines gape into wet ragged trenches, the flesh between them dries into hard ridges, and the skin stays leathery and pale where it should have blistered and set.