Step 1

Rinse the fish fillets and scale them, if necessary. Pat them dry very well. White fish will benefit from salting and chilling it for at least half an hour, then rinse the fish again and pat dry.

Step 2

Melt the butter in a pan large enough to fit the fish in one layer. Add the herbs and garlic. If you have a digital probe, stick it in and heat the butter up only to 50C/125F. Lower the fish into the butter and stick the probe in the thickest part of a fillet.

Step 3

If you don’t have a probe, just keep the butter on absolute minimum heat and don’t let it foam up.

Step 4

The fish is ready when the internal temperature is 50C, with no probe cook it for about 10 minutes, depending how thick the fillets are. If you’re unsure if it’s cooked, prod it gently and see if it starts to flake – ready if it does.

Step 5

Lift the fillets carefully out onto a warm serving plate, drizzle a little butter over them and garnish with lemon slices. Serve with a salad – here a mix of raw beetroot, remoulade and coleslaw.Note: the butter can be strained, cooled and reused, admittedly not for baking cakes, but fine for savoury cooking.