Crisp-Skinned Salmon

Take the salmon out of the fridge 10 minutes before you cook it.

Blot the skin with kitchen paper, pressing rather than wiping, until the paper comes away dry.

Season both sides of the fillets with the 3g of fine salt.

Pour the oil into a cold heavy frying pan and tilt it to coat the base.

Lay the fillets skin-side down in the cold pan.

Set the pan over medium heat. Starting cold gives the fat under the skin time to render as the pan comes up; skin dropped into a pan already smoking seizes and sticks before any of it has rendered out.

Press each fillet flat with a fish slice for the first 20-30 seconds, until it stops trying to lift at the edges. Salmon skin contracts as it heats and bows the fillet into a curve, and the middle of the skin then never touches the metal at all.

Leave the fish alone once it sits flat.

Cook skin-side down for 6-8 minutes, until the flesh has turned opaque up the sides to about two-thirds of its depth.

Do not try to lift it before then. The skin releases itself the moment it is properly crisp, and a fillet prised up early leaves the skin welded to the pan and comes away bare.

Turn the fillets with a thin slice.

Drop the cold butter into the pan.

Cook flesh-side down for 60-90 seconds, spooning the foaming butter over the fillets, until the thickest part gives easily under a finger and the very centre is still a shade darker than the edges.

Lift them onto warm plates skin-side up, so the crisp side never sits in steam.

Rest for 2 minutes, which is long enough for the centre to finish setting in the residual heat.

Finish the skin with flaky salt.

Scatter the dill over the plated fish rather than into the pan, since the fronds blacken and turn grassy the moment they hit hot butter.

Serve with the lemon wedges.