Why mackerel is made for a beach barbecue

Few things taste better outdoors than mackerel cooked within sight of the water it came from. It is oily, forgiving, and quick — three or four minutes a side over a decent fire is often all it needs. That oiliness is exactly why it works so well on a barbecue: the fat bastes the flesh from the inside, keeping it moist while the skin crisps and blisters. It also stands up to smoke, char and a heavy hand with lemon.

Buy it as fresh as you can. Look for bright, slightly bulging eyes, a silvery skin with the dark tiger stripes still sharp, and flesh that springs back when pressed. A stiff tail is a good sign; a limp one is not. Fresh mackerel smells clean and sea-like, never sharp or ammonia-tinged. If you have caught your own, gut and chill it straight away — oily fish decline far faster than white fish. A cool box with ice packs, kept in the shade, will hold it safely for a few hours, but no longer. Do not leave it sitting in the sun while you build the fire.

Check the rules before you pack the charcoal

This is the part most people skip, and it is the part that causes the most trouble. Coastal rules vary enormously over quite short distances, so check before you travel rather than after you have parked.

• Many councils ban disposable barbecues outright on their beaches, particularly during dry summer spells when grass and gorse above the tideline become a serious fire risk.
• Some allow them only in designated zones, or only between certain hours. Others permit raised, reusable barbecues but nothing that sits directly on the sand.
• Nature reserves, dunes and shingle banks are almost always off limits. Nesting birds, fragile dune vegetation and buried litter all suffer from a hot tray of coals.
• Check the tide table as carefully as the byelaws. Setting up below the high-water mark is a good way to lose your lunch to the incoming sea.
• Look at the wind. A breezy beach is lovely; a gusty one will scatter ash and sparks into dry marram grass.

Three marinades that suit oily fish

Mackerel needs very little, so keep your marinades simple and short. Twenty to thirty minutes is plenty. Any longer and the acid starts to firm and "cook" the surface of thin fillets, giving you a slightly chalky texture before the fish even hits the grill. Score the skin lightly with a sharp knife so the flavours get in and the fillets stay flat.

• Lemon and herb: three tablespoons of olive oil, the zest and juice of half a lemon, a crushed clove of garlic, a good pinch of sea salt, plenty of black pepper and a handful of chopped thyme or parsley. This is the classic, and it lets the fish speak for itself.
• Ginger, soy and honey: two tablespoons of light soy sauce, a tablespoon of honey, a thumb of grated ginger and a squeeze of lime. Watch it closely on the grill — the honey catches and burns quickly.
• Smoked paprika and garlic: two teaspoons of smoked paprika, two tablespoons of olive oil, a grated garlic clove, a splash of sherry vinegar and a pinch of cayenne. Warm, faintly smoky and excellent with a tomato salad.

The kit that makes it easy

A little preparation turns a fiddly job into a relaxed one. Mackerel skin is delicate when it is hot, and it will tear if you try to move the fish too soon.

• A raised, reusable barbecue or a small kettle grill — something with a lid is ideal for thicker whole fish.
• Lumpwood charcoal and a chimney starter. Avoid instant-light bags; they taint oily fish.
• Long tongs and a fish basket or hinged grill grate, which lets you turn a whole fish in one confident movement.
• Kitchen paper soaked in oil, for wiping the hot bars just before the fish goes on.
• A sharp knife for testing doneness, a board, a cool box, and a couple of litres of water for dousing the coals.

Cooking the fish: hot, fast, hands off

Let the coals burn down until they are grey and ashed over — you want a steady, fierce heat, not a roaring flame. Wipe the bars with oiled paper, lay the fish skin-side down and then leave it alone. Resist the urge to poke it. After three to four minutes the skin will release naturally; if it resists, give it another thirty seconds.

Fillets need roughly three minutes a side. A whole fish of around 350g wants four to five minutes a side, depending on how close it sits to the coals. To test, slide a knife into the thickest part behind the head and lift the meat gently away from the backbone — it should come away cleanly, opaque and juicy, with no pink translucence at the bone. If it is not there yet, move it to a slightly cooler part of the grill rather than turning up the heat, which will only dry the outside.

Serving, and leaving the beach as you found it

Mackerel is at its best about ninety seconds after it leaves the grill, so have everything else ready first: buttered bread or rolls, lemon wedges, a tomato and red onion salad, maybe a jar of pickle. Eat it hot with your fingers if you like. Anything left over should be eaten within the hour and never left standing in the sun.

When you have finished, douse the coals thoroughly with water until they are cold to the touch. Never bury them in the sand — they stay hot underneath for hours and someone will find them with a bare foot. Bag up every scrap, including foil and bottle tops, and take it home. Brush the sand off your spot, leave the stones where they were, and the next person will never know you were there.