In Dorset, mackerel usually arrive in May or June, as they chase the sand eels and whitebait inshore, sometimes chasing them right up on to the beach. They may disappear for a few weeks in August, before returning with a vengeance to gorge on the sprats. I’ll take them whenever I can get them, and never tire of eating them, whether grilled over charcoal, raw as sushi, pickled with dill, or even boiled in seawater on the beach (try it). This Provençal-style dish is one of the few ‘fancy’ treatments I’ll allow myself – not that it’s remotely difficult or time-consuming.

Ingredients:

To serve 4 as a starter, 2 as a main course.
Cut the fillets from either side of 2 whole, ungutted mackerel, and season them with a little salt and pepper.

Slice 2–3 large onions – enough almost to fill a large frying pan (they will reduce to about a quarter of their volume as they cook).

Heat a film of olive oil in the pan and add the onions with 3 or 4 bay leaves and a sprig or two of thyme.

Sweat the onions gently, tossing and stirring frequently, for at least 10 minutes, until they are softened and golden, very tender and sweet. Don’t let them burn. Add a handful of black olives, stoned and roughly chopped, and a splash of white wine.

Cook for a few minutes until the wine has evaporated, then season with a little salt and pepper.

Push the onions to the edges of the pan, making space for the mackerel fillets to cook in the middle. Lay the fillets in the pan, flesh-side down. Turn them after a few minutes to cook the skin side, spreading the onions over the fish to help the transfer of heat. They should be cooked through in 7–8 minutes.

This dish can be served hot, straight from the pan, but is arguably even better at room temperature. Serve with a good chilled rosé – which will taste particularly fine with the rich, oily fish, sweet onions and salty olives.