River Cottage

Make the salsa verde first: put the herbs on a large board and chop them well. Combine the garlic with the anchovies and capers and chop/mash them together into a coarse paste. Bring the chopped herb and anchovy mixtures together and chop again. Pile the whole lot into a small mixing bowl and add the mustard, lemon juice and some black pepper to taste. Stir in just enough olive oil to make a thick green sauce (it shouldn’t be runny or sloppy). Taste and adjust the seasoning, then set aside.

Now fillet the mackerel bait-cutter style, but leaving the fillets joined at the tail end. Make sure you remove all the pin bones. You should be left with a boneless, headless pair of fillets, still joined at the tail, and with one V-shaped channel in each fillet where the pin bones have been removed. Run a good smear of the salsa verde down the V-shaped groove in each fillet of mackerel, then smear a little more over the flesh. Close up the fish and secure in a couple of places with kitchen string. You can do all this preparation several hours in advance and chill the fish until needed. In fact, the flavour will be better this way.

To cook, set a large, heavy frying pan over a medium heat. Brush the fish lightly with oil, season them and fry for 5–6 minutes on each side, until the flesh is cooked through. Alternatively, brush them with a splash of oil, season and roast in an oven preheated to 200–220°C/Gas Mark 6–7 for 12–15 minutes. They can also be barbecued.